ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (367)
  • Column liquid chromatography  (344)
  • Calcification
  • Springer  (367)
  • Nature Publishing Group
  • PANGAEA
  • 1995-1999  (349)
  • 1965-1969  (18)
Collection
  • Articles  (367)
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 2 (1968), S. 296-298 
    ISSN: 1432-0827
    Keywords: Calcium ; Lipid ; Bacteria ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé On a fait ce travail pour determiner si le facteur responsable pour la liaison de calcium par un calcifableBacterionema matruchotii est dans la fraction lipide de la cellule. Des cellules congelees et sechees ont ete extraites par le chloroform-methanol. La fraction de chloroform-methanol, les cellules extraites et les cellules non traitees ont ete examinees pour la liaison de calcium. La fraction du chloroform-methanol et les cellules non traitees avaient la liaison de calcium. Les cellules extraites n'en avaient pas.
    Abstract: Zusammenfassung Diese Arbeit wurde durchgeführt um festzustellen, ob sich der Faktor für die Calcium-bindung, durch das calcifizierendeBacterionema matruchotii, in der Lipoidfraktion befindet. Die lyophiilisierten Zellen wurden mit Chloroform-Methanol extrahiert. Die Chloroform-Methanol-Fraktion, die extrahierten Zellen, sowie die nicht behandelten Zellen wurden auf eine Calciumbindung hin untersucht. Die Chloroform-Methanol-Fraktion und die nicht behandelten Zellen demonstrierten eine Calciumbindung. Die extrahierten Zellen hingegen nicht.
    Notes: Abstract This work was done to determine whether the factor responsible for calcium binding by a calcifiableBacterionema matruchotii is in the lipid fraction of the cell. Freeze-dried cells were extracted with chloroform-methanol. The chloroform-methanol fraction, the extracted cells and untreated cells were examined for calcium binding. The chloroform-methanol fraction and the untreated cells bound calcium. The extracted cells did not.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 4 (1969), S. 260-268 
    ISSN: 1432-0827
    Keywords: Cartilage ; Histochemistry ; Staining ; Protein ; Polysaccharide ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des coupes de cartilage épiphysaire frais de jeunes rats, effectuées à la main, sont colorées à pH=4,5 dans des solutions à 0,01% de divers colorants cationiques, appartenant aux groupes de la thiazine, oxazine, azine, triphénylméthane, acridine, et phthallocyanine. Les granules intracellulaires métachromatiques, mises en évidence antérieurement par le bleu de toluidine, sont également identifiées à l'aide de l'azur A, le bleu de méthylène et le bleu de crésyl. Les granules se colorent moins bien à la thionine, le rouge neutre, la safranine O, le bleu de toluylène et l'acridine orange. Dans les conditions utilisées, la matrice de la zone de réserve et la matrice de la zone hypertrophique inférieure (en voie de calcification) se colorent, alors que les matrices des zones prolifératives et hypertrophiques supérieures ne prennent pas les colorants. La gallocyanine, le violet cristal, la fuchsine basique, l'azocarmin B, le bleu de gallamine et la bleu alcian ne se colorent pas ou donnent des réactions colorées différentes de celles décrites ci-dessus. Il semble que le pK et le poids moléculaire des colorants jouent un rôle important, mais ils ne paraissent pas être les seuls facteurs intervenant dans la coloration des granules. Un changement, lié à la calcification, semble intervenir au niveau du matériel métachromatique (probablement des polysaccharides protéiques), aussi bien dans la matrice que les cellules cartilagineuses épiphysaires.
    Abstract: Zusammenfassung Handpräparierte Schnitte von frischem Epiphysenknorpel junger Ratten wurden bei einem pH von 4,5 in 0,01% igen Lösungen verschiedener kationischer Farbstoffe folgender Klassen gefärbt: Thiazin, Oxazin, Azin, Triphenylmethan, Acridin und Phthalocyanin. Die intracellulären β-und γ-metachromatischen Granula, erstmals mit Toluidinblau im frischen Gewebe nachgewiesen, konnten auch gut mit Azur A, Methylenblau und Brillantkresylblau dargestellt werden. Die Granula konnten ebenfalls, aber weniger gut, mit Thionin, Neutralrot, Safranin D, Toluylenblau und Acridinorange gefärbt werden. Unter diesen Färbungsbedingungen werden die inaktive Matrixzone und die untere hypertrophische (verkalkende) Matrixzone angefärbt, während die proliferative und die obere hypertrophische Matrixzone sich nicht färben. Gallocyanin, Kristallviolett, basisches Fuchsin, Azokarmin B, Gallaminblau und Alzianblau färbten entweder gar nicht, oder gaben ein anderes als das obenbeschriebene Färbemuster. Es wird vorgeschlagen, daß das pK und das Molekulargewicht der Farbstoffe wichtig aber nicht unbedingt die einzigen Faktoren sind, die die Färbung der Granula bestimmen. Die Resultate zeigen, daß eine Veränderung im metachromatischen Material (vermutlich Proteinpolysaccharide) vorliegt, und zwar sowohl in der Matrix als in den Zellen des Epiphysenknorpels; diese Veränderung scheint im Zusammenhang mit der Verkalkung zu stehen.
    Notes: Abstract Hand-cut sections of fresh epiphyseal cartilage from young rats were stained at pH 4.5 in 0.01% solutions of various cationic dyes of the thiazine, oxazine, azine, triphenylmethane, acridine, and phthallocyanin classes. The intracellular β-and γ-metachromatic granules, previously demonstrated in fresh tissues with toluidine blue, were also demonstrated well with azure A, methylene blue, and brilliant cresyl blue. The granules were also demonstrated, but not as well, by thionin, neutral red, safranin O, toluylene blue, and acridine orange. Under the conditions of staining, the reserve zone matrix and the lower hypertrophic (calcifying) zone matrix stained, whereas the proliferative and upper hypertrophic zone matrix did not stain. Gallocyanin, crystal violet, basic fuchsin, azocarmine B, gallamine blue, and alcian blue either did not stain, or gave a different pattern of staining from that described above. It is suggested that the pK and molecular weight of the dyes are important, but not necessarily the only factors in determining the staining of the granules. The results indicate that there is a change in the metachromatic material (presumably proteinpolysaccharide) in both the matrix and cells of epiphyseal cartilage, which appears to be related to calcification.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 4 (1969), S. 20-38 
    ISSN: 1432-0827
    Keywords: Calcification ; Epiphyseal Cartilage ; Bone ; Electrolytes ; Organic matrices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un procédé de dissection a été mis au point pour permettre l'analyse zonale du cartilage de l'épiphyse des os de la jambe d'un foetus bovin. Des échantillons de tissu complet et lavé venant des différentes zones ont été analysés pour déterminer leur contenu en électrolyte et en constituants organiques, ainsi que pour leur densité, cendres et humidité. Les résultats ont montré que lorsque la quantité de cendres et la densité augmentaient, l'eau contenu dans le tissu diminuait. Les quantités de cendres dans les zones de cartilage en voie de calcification étaient plus grandes qu'il avait été. Quand elles étaient exprimées comme un pourcentage du poids sec, elles étaient les plus importantes dans le cartilage lavé calcifié que dans le autre zones. Au début de la minéralisation du cartilage, la quantité de Na (m moles/l de tissu frais) diminuait tandis que celles du Ca et du P inorganique augmentaient. Les niveaux de Mg augmentaient pendant que la calcification se poursuivait, mais seulement à une faction du taux du Ca et du P. Les rapports Ca/P inorganique étaient les plus grands dans le cartilage au repos (Cartilage non-différentié hyalin), suggérant un lien initiale entre Ca et les chrondromucoprotéines. Cependant, au début de la calcification, pendant la prolifération du cartilage les rapports Ca/P étaient beaucoup plus petits (ca. 1.50) mais augmentaient graduellement avec l'advancement de la minéralisation. Des changements importants survenaient dans la composition de la phase organique, pendant la calcification endochondrale. Comme il a été déterminé par l'analyse de l'hydroxyproline la quantité de collagéne diminuait progressivement pendant la calcification du cartilage, mais augmentait rapidement pendant la formation d'os. Comme il a été déterminé par l'analyse de l'héxosamine et du sulfute les chrondromucoprotéines étaient aux niveaux les plus éléves pendant la prolifération du cartilage et diminuaient constamment au cours de la calcification. Cependant, bien que la calcification était déja très avancée dans le cartilage hypertrophique, de grandes quantites de mucopolysaccharides étaient encore présentes. Les rapports sulfure/hhéxosamine montraient un léger déclin pendant les premiéres étapes de la calcification, mais augmentaient beaucoup pendant le cours de la minéralisation. Les quantités d'acide sialique étaient plus grandes dans le cartilage de l'épiphyse que dans le cartilage au repos ou dans l'os. Les lipides augmentaient rapidement pendant la calcification du cartilage, mais étaient très réduites dans l'os complètement formé. La signification de ces résultats est discutée.
    Abstract: Zusammenfassung Eine Seziermethode, die eine Schichten-Analyse der Beinepiphysenplatte von Rinderfeten erlaubt, wurde entwickelt. Proben vor und nach Waschen des Gewebes der verschiedenen Schichten werden untersucht in bezug auf Elektrolyte und organische Bestandteile, als auch in bezug auf Dichte, Aschengehalt und Feuchtigkeit. Die Resultate zeigten eine Zunahme des Aschengehaltes und der Dichte, während der Wassergehalt abnahm. Unerwartet hoch waren die Aschenwerte im in Verkalkung begriffenen Knorpel. Ausgedrückt in Prozent Trockengewicht, ergab gewaschener, verkalkter Knorpel den höchsten Wert aller Zonen. In den Frühstadien der Knorpelmineralisation nahm der Natriumgehalt (m Mol/l Frischgewebe) ab, während Ca und anorganischer P zunahmen. Mit fortschreitender Verkalkung erhöhte sich auch der Magnesium-Spiegel, allerdings nur zu einem Bruchteil des Ausmaßes, in welchem Ca und P zunahmen. Die höchsten Ca/P anorg. Verhältnisse wurden im Ruheknorpel (undifferenzierter hyaliner Knorpel) gefunden, was auf eine initiale Bindung von Ca durch Chondromucoproteine hinweist. Die Ca/P-Verhältnisse proliferierenden Knorpels waren jedoch bei Verkalkungsbeginn viel tiefer (ca. 1.50). Diese nahmen allerdings mit fortschreitender Mineralisierung stetig zu. In der endochondralen Verkalkungsphase fanden markante Veränderungen in der Zusammensetzung des organischen Anteils statt. Basierend auf der Hydroxyprolinanalyse nahm der Collagengehalt in der knorpeligen Verkalkungsperiode fortschreitend ab, während er jedoch bei der Knochenbildung rasch zunahm. Die an Hand von Hexosamin- und Schwefelanalysen bestimmten Chondromucoproteingehalte ergaben Höchstwerte im proliferierenden Knorpel und fielen stetig ab mit zunehmender Verkalkung. Trotz der im hypertrophischen Knorpel schon weit fortgeschrittenen Verkalkung waren immer noch große Mengen an Mucopolysacchariden vorhanden. Die Schwefel/Hexosamin-Verhältnisse zeigten eine minimale Abnahme in den frühen Verkalkungsphasen, nahmen jedoch markant zu bei fortschreitender Mineralisation. Der Sialinsäurespiegel war im Epiphysenknorpel, verglichen mit demjenigen des Ruheknorpels oder Knochens, erhöht. In der knorpeligen Verkalkungsphase nahmen die Lipide rasch zu, während jedoch die Werte des vollständig ausgebildeten Knochens stark vermindert waren. Die Bedeutung dieser Ergebnisse wird besprochen.
    Notes: Abstract A dissection procedure has been devised to permit zonal analysis of the epiphyseal plate of fetal calf leg bones. Samples of whole and washed tissue from the various zones were analyzed for their content of electrolyte and organic constituents, as well as for density, ash and moisture. Results showed that as ash content and density increased, water content decreased. Ash levels in calcifying cartilage zones were unexpectedly high. When expressed as a percentage of dry weight, washed calcified cartilage had the highest content of any zone. In the early stages of the mineralization of cartilage, Na content (mmoles/l of fresh tissue) decreased as Ca and inorganic P increased. Magnesium levels increased as calcification proceeded, but only at a fraction of the rate of Ca and P. Ratios of Ca/inorganic P were highest in resting cartilage (non-differentiated hyaline cartilage), suggesting an initial binding of Ca to chondromucoproteins. However, at the onset of calcification in proliferating cartilage, Ca/P ratios were much lower (ca. 1.50), but gradually increased with advancing mineralization. Marked changes occurred in the composition of the organic phase during endochondral calcification. As determined by hydroxyproline analysis, collagen content progressively decreased during cartilaginous calcification, but increased rapidly during bone formation. As determined by hexosamine and sulfur analysis, chondromucoproteins were at highest levels in proliferating cartilage and decreased steadily as calcification increased. However, although calcification was already well advanced in hypertrophic cartilage, large amounts of mucopolysaccharide still were present. Sulfur/hexosamine ratios showed a slight decline during the early stages of calcification, but increased markedly with further mineralization. Sialic acid levels were elevated in epiphyseal cartilage over those in resting cartilage or bone. Lipids increased rapidly during cartilaginous calcification, but were greatly reduced in fully-formed bone. The significance of these findings is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-0975
    Keywords: Key words Coral ; Calcification ; Biomineralisation ; Autoradiography ; Freeze-substitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract  The uptake of 45Ca and/or 14C by the skeleton of coral colonies has been commonly used to investigate the processes of calcification. This study reports the differential uptake of these tracers within different regions of the skeleton and tissues of individual corallites and polyps of the hermatypic coral Galaxea fascicularis. Incubation in 45Ca in the light resulted in 80 percent of the 45Ca taken up being deposited in the skeleton. Autoradiography of transverse and longitudinal slices of freeze-substituted polyps and corallites showed that in the light 45Ca was incorporated into the exsert septa, the outside of the thecal walls of the corallite and the inner edges of the septa. Incorporation did not occur in the costae. The radioactivity in the skeleton was considerably greater than in the tissues. In the dark, or in the presence of the photosynthetic inhibitor Diuron, 45Ca was taken up by the exsert septa and was patchily distributed in the corallite walls which suggests that it was not a result of isotopic exchange. The differential incorporation of 45Ca onto the exsert septa was confirmed by scintillation counting. Negligible radioactivity remained in the extrathecal coelenteron after a brief 5 min rinse in non-radioactive seawater. Only 0.1% of 14C taken up in the light was incorporated into the skeleton and this was confirmed by autoradiography. In the presence of Diuron or in the dark, very little 14C was incorporated into tissues or skeleton and in autoradiographs was either not evident in the skeleton or the distribution was similar to that seen in autoradiographs of 45Ca uptake. These results show that the deposition of 45Ca, and therefore calcium carbonate, occurs at specific loci on the skeleton of a corallite. In the dark, deposition occurs specifically at the growing points of the corallite. Differential deposition of calcium carbonate within individual corallites has not been previously reported.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 3 (1969), S. 151-162 
    ISSN: 1432-0827
    Keywords: Calcification ; Physiologic ; Phosphonic Acids ; Phosphates ; Crystallization ; Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé On a étudié la formation de l'hydroxyapatite de calcium cristallin à partir de solutions d'ions de calcium et de phosphate et l'inhibition de la croissance de cristaux de l'hydroxyapatite de calcium au moyen de polyphosphonates et de polyphosphates. Les polyphosphonates, éthane hydroxy-1-diphosphonate-1,1 de disodium et dichlorométhanediphosphonate de disodium, sont inhibiteurs efficaces contre la croissance de cristaux de l'hydroxyapatite de calcium. Les polyphosphates sont aussi inhibiteurs efficaces contre la croissance de cristaux de l'hydroxyapatite de calcium tant que le niveau exigé de polyphosphate intact est présent dans le système. Cependant, à cause de leur instabilité hydrolytique, qui est soulignée par une température élevée, valeur de pH basse, et certaines enzymes, la concentration du polyphosphate diminue avec le tempsin vitro, et son activité comme inhibiteur est perdue. Au contraire aux polyphosphates, les polyphosphonates sont hydrolytiquement stables. Les polyphosphonates sont chimiosorbés sur la surface des microcristallites de l'hydroxyapatite de calcium, ainsi empêchant l'occurrence d'autre croissance de cristaux semblable à l'action d'autres poisons connus de croissance de cristaux. On propose l'extension de cette action sur la formation de l'apatite et cette stabilité des polyphosphonates aux applications médicales et dentaires concernant le metabolisme pathologique de calcium et de phosphate.
    Abstract: Zusammenfassung Die Bildung des kristallinen Calciumhydroxyapatit aus Lösungen, welche Calcium- und Phosphationen enthalten, und die Hemmung der Bildung von kristallinen Calciumhydroxyapatit durch Polyphosphonate und Polyphosphate wurden untersucht. Polyphosphonate, Dinatriumäthan-1-hydroxyl-1,1-diphosphonat und Dinatriumdichloromethandiphosphonate verhindern das Kristallwachstum des Calciumhydroxyapatits. Die Polyphosphate verhindern ebenfalls das Kristallwachstum des Calciumhydroxyapatits, solange die notwendige Konzentration des nicht hydrolysierten Polyphosphats vorhanden ist. Wegen ihrer hydrolytischen Unbeständigkeit, die durch hohe Temperatur, niedrige pH und bestimmte Enzyme erhöht wird, vermindert sich jedoch die Konzentration des Polyphosphats allmählichin vitro, und ihre Hemmungsaktivität geht verloren. Im Gegensatz zu den Polyphosphaten sind die Polyphosphonate hydrolytisch beständig. Die Polyphosphonate werden an der Oberfläche der Mikrokristallite des Calciumhydroxyapatits chemisorbiert und verhindern, wie andere bekannte Kristallwachstumsgifte, auf diese Weise weiteres Kristallwachstum. Die Beständigkeit der Polyphosphonate und ihre Chemisorption an dem Apatit empfehlen ihren Gebrauch in der ärztlichen und zahnärztlichen Praxis, soweit sie den pathologischen Calcium- und Phosphatstoffwechsel betreffen.
    Notes: Abstract The formation of crystalline calcium hydroxyapatite from solutions of calcium and phosphate ions and the inhibition of calcium hydroxyapatite crystal growth by polyphosphonates and polyphosphates have been studied. The polyphosphonates, disodium ethane-1-hydroxy-1,1-diphosphonate and disodium dichloromethane diphosphonate, are effective inhibitors of calcium hydroxyapatite crystal growth. The polyphosphates are also effective inhibitors of calcium hydroxyapatite crystal growth as long as the required level of intact polyphosphate is present in the system. However, because of their hydrolytic instability, which is enhanced by high temperature, low pH, and certain enzymes, the concentration of the polyphosphate decreases with timein vitro, and its activity as an inhibitor is lost. In contrast to the polyphosphates, the polyphosphonates are hydrolytically stable. The polyphosphonates are chemisorbed on the surface of the microcrystallites of calcium hydroxyapatite and, in the manner of other known crystal growth poisons, thus prevent further crystal growth. The stability of the polyphosphonates and their chemisorption on apatite suggest their use in medical and dental applications involving pathological calcium and phosphate metabolism.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 3 (1969), S. 184-193 
    ISSN: 1432-0827
    Keywords: Mitochondria ; Calcification ; Calcium ; Chondrocytes ; Growth plate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des cultures d'épiphyse prélevées sur des rats et des souris ont été étudiées sous le microscope électronique. Un profile de granules mitochondriques de densité électronique a été trouvé. Les chondrocytes dans la zone proliférative avaint peu de granules, alors que ceux des zones successives ont montré une augmentation progressive de leur nombre et densité jusqu'à ce que la zone de calcification provisoire ait été atteinte. Cette zone a montré une distribution périphérique de mitochondries et une réduction du nombre et de la densité des granules mitochondriques. Du calcium isotopique 47 a été utilisé autoradiographiquement pour déterminer la location de calcium dans ces cellules. Des grains ont été trouvés sur les membranes R.E. et sur la plupart des mitochondries. La preuve d'un profile de ces granules et de leur rapport spatial avec la face de minéralisation indique une action éventuelle de mitochondries dès le début de la calcification de la matrice.
    Abstract: Zusammenfassung Epiphysekulturen von Ratten und Mäusen wurden unter dem Elektronenmikroskop untersucht. Ein Profil von mitochondrischen Körnchen mit elektronischer Dichte wurde gefunden. Chondrozyten in der Proliferationszone wiesen wenig Körnchen auf, während die der nachfolgenden Zonen allmählich an Zahl und Dichte zunahmen, bis die Zone der provisorischen Verkalkung erreicht wurde. Diese Zone zeigte eine periphere Verteilung der Mitochondrien und eine Abnahme in Zahl und Dichte der mitochondrischen Körnchen. Isotopes Kalzium 47 wurde autoradiographisch verwendet, um die Lage des Kalziums in diesen Zellen zu bestimmen. Körnchen wurden auf den E.R.-Membranen und auf einem Großteil der Mitochondrien gefunden. Der Nachweis eines Profils dieser Körnchen und ihres räumlichen Verhältnisses zur Mineralisierungsfläche weist auf einen möglich Einfluß der Mitochondrien mit Beginn der Matrixverkalkung hin.
    Notes: Abstract Rat and mice epiphyseal growth plates were studied with the electron microscope. A gradient of mitochondrial electron-dense granules was found. Chondrocytes in the proliferative zone had few granules, while those of the succeeding zones showed a gradual increase in number and density until the zone of provisional calcification was reached. This zone showed a peripheral distribution of mitochondria and a decrease in the number and density of mitochondrial granules. Isotopic47calcium was used autoradiographically to determine the location of calcium in these cells. Grains were found over the endoplasmic reticulum membranes and over most mitochondria. The demonstration of a gradient of these granules and their spatial relation to the mineralization front suggests a possible involvement of mitochondria in the onset of matrix calcification.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 4 (1969), S. 78-83 
    ISSN: 1432-0827
    Keywords: Bone ; Calcification ; Osteomalacia ; Phosphorus ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les effects d'une dose de 1 mg de vitamine D3 (40 000 Unités,) administrée par voie intra-veineuse, ont été étudiés sur l'histologie osseuse et le métabolisme du phosphore chez 19 sujets contrôles dont l'histologie était normale et 28 malades présentant les caractères histologiques de l'ostéomalacie par carence vitaminique D. L'administration de la vitamine D n'a entraîné aucune modification histologique ou biologique significative chez les sujets contrôles. Mais chez les ostéomalaciques, il est apparu en moins de sept jours une augmentation très significative du front de calcification à l'interface tissue-ostéoïde-tissue-calcifié. Cette modification s'accompagnait d'une ascension progressive de la phosphatémie et de la réabsorption tubulaire du phosphore atteignant dans le même délai des valeurs normales.
    Abstract: Zusammenfassung Bei 19 Patienten mit normaler Knochenhistologie und bei 28 Patienten mit histologisch gesicherter Osteomalacie wurde die Wirkung von 1 mg Vitamin D3 (40000 Iv) i.v. auf die Knochenhistologie und den Phosphatmetabolismus untersucht. Bei den Kontrollpatienten konnten keine signifikanten Änderungen nach Vitamin D festgestellt werden, wogegen die Osteomalacie-patienten innerhalb von 7 Tagen eine deutliche Zunahme der Verkalkungszone an der Grenze zwischen Osteoid- und Knochengewebe zeigten. Diese Änderung war von einer fortschreitenden Zunahme des Serum-Phosphates, verbunden mit einer gesteigerten renalen tubulären Rückabsorption des Phosphates begleitet; beide kehrten anschließend gleichzeitig wieder zur Norm zurück.
    Notes: Abstract The effect of a 1 mg dose of intravenous Vitamin D3 (40,000 i.u.) on bone histology and phosphate metabolism was investigated in 19 patients with normal bone histology and 28 patients with histological evidence of osteomalacia. No significant changes occurred in the control patients after Vitamin D but the patients with osteomalacia showed a marked increase, within seven days, in the proportion of osteoid having a calcification front. This was accompanied by a progressive rise in the serum phosphate, which was associated with an increase in the renal tubular reabsorption of phosphate to normal.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 4 (1969), S. 231-244 
    ISSN: 1432-0827
    Keywords: Calcification ; Pyrophosphate ; Inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les propriétés d'induction de calcification des liquides biologiques peuvent être mesurées, in vitro et in vivo, par leur possibilité de redurcir des blocs d'émail décalcifié. Cette propriété est exprimée par les concentrations de calcium (et de phosphate) de solutions synthétiques inductrices de calcification, de concentrations et d'activité connues. Un plasma humain typique a une activité inductrice correspondant à celle d'une solution contenant du calcium, 0,70 mM, Ca/P, 1,67 et fluorure, 0,05 mM. L'activité relativement peu élevée des sérums et des plasmas s'explique par la présence d'inhibiteurs ioniques. L'ion phosphate est l'un d'eux, mais ne peut rendre compte de l'inhibition totale. Des anions et des cations sont responsables de l'inhibition, avec un rôle majeur pour les cations. Les ions suivants, en concentration physiologique, jouent un rôle inhibiteur: P7O 7 4− , HCO 3 − , SiO 4 2− , CrO 4 2− , Mg2+, Zn2+. Un mélange de ces ions provoque une inhibition totale identique à celle du plasma.
    Abstract: Zusammenfassung Der Einfluß biologischer Flüssigkeiten auf den Verkalkungsvorgang kann in vitro und in vivo anhand ihrer Fähigkeit, enthärtete Blöcke von Zahnschmelz wieder zu härten, gemessen werden. Diese Aktivität wird ausgedrückt als Konzentration des Calciums (und Phosphates) synthetischer calcifizierender Lösungen mit bekannter Konzentration und Aktivität. Die Aktivität eines charakteristischen menschlichen Plasmas entsprach derjenigen einer Lösung folgender Zusammensetzung: Calcium 0,70 mM; Ca/P=1,67 und Fluorid 0,05 mM. Die relativ niedrige Aktivität von Serum und Plasma ist bedingt durch das Vorhandensein einer Anzahl ionischer Inhibitoren. Das Pyrophosphation ist ein solcher; er kann aber nicht für die gesamte Inhibition verantwortlich gemacht werden. Sowohl anionische als auch kationische Inhibitoren sind vorhanden, wobei die Kationen den Hauptanteil ausmachen. Folgende Ionen erwiesen sich in einer physiologischen Konzentration als Inhibitoren synthetischer Systeme: P7O 7 3− , HCO 3 − , SiO 4 1− , CrO 4 2− , Mg2+, Zn2+. Zusammengenommen verursachten diese Ionen eine Gesamtinhibition ähnlich derjenigen des Plasmas.
    Notes: Abstract The calcifying activities of biological fluids can be measured,in vitro andin vivo, by their ability to reharden softened blocks of tooth enamel. The activity is expressed in terms of the calcium (and phosphate) concentrations of synthetic calcifying solutions of known concentration and activity. A typical human plasma had an activity corresponding to that of a solution of the following concentration: calcium, 0.70 mM; Ca/P, 1.67 and fluoride, 0.05 mM. The relatively low activity of serums and plasmas was shown to arise from the presence of a number of ionic inhibitors. Pyrophosphate ion is one such inhibitor but cannot account for the major inhibition. Both anionic and cationic inhibitors were shown to be present, with the cations respresenting the major portion. The following ions at their reported physiological concentration were shown to be inhibitors in synthetic systems: P7O 7 4− , HCO 3 − , SiO 4 2− , CrO 4 2− , Mg2+, Zn2+. In combination, these ions caused a total inhibition similar to those for plasmas.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 3 (1969), S. 266-273 
    ISSN: 1432-0827
    Keywords: Calcification ; Arteries ; Membranes ; Elastic tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Avec la modification d'une méthode de von Kossa nous avons macroscopiquement representé les dessins de calcification de la membrane élastique intérieure, ainsi que les grosses artères du bassin, des artères des extrémités inferieures, des artères du bras, de la rate et des reins. Dans les artères du type élastique, dans les A.a. ilicae communes et internae, se présentaient les dégénérations calcaires de la membrane élastique intérieure sous forme d'incrustations noires arrondies ou polygonales qui ont été formes en groupes. Elles étaient toujours présentes chez des enfants agés de plus de trois mois et chez des aux adultes. Dans les artères musculaires, se montraient les parties calcifiées de la membrane élastique intérieure en forme de «bandes de calcaire» noires et groupes en paires le long des bordures des fissures de la membrane. Dans le cas où existait une calcinose forcée, on pouvait montrer avec cette méthode tout le système de fissures de la mambrane élastique intérieure. Chez tous les morts âgés de 10 à 20 ans, nous avons trouvé des bandes de calcaire dans les artères musculaires des extrémités inferieures. Ces bandes de calcaire ont été constatées aussi dans des personnes plus âgées. Au point de la fusion des bandes de calcaire et des incrustations calcaire polygonales des dépôts calcaires en forme de feuille («feuilles de calcaire») se forment dans la membrane elastique. Les bandes de calcaire et les feuilles de calcaire représentent des points de cristallisation pour des dépôts calcaire granuleux. Ils se forment dans la plupart des cas sur le la côté externe tourné vers la media.
    Abstract: Zusammenfassung Mit einer modifizierten von Kossa-Methode wurden die Verkalkungsmuster der inneren elastischen Membran der großen Beckenarterien, der Arterien der unteren Extremität, der Oberarm-, Milz-und Nierenarterien makroskopisch dargestellt. In den Arterien vom elastischen Typ, i.e. in den Aa. ilicae communes et internae, erschienen die Verkalkungen der inneren elastischen Membran als schwarze rundliche oder polygonale Inkrustationen, die zu Gruppen angeordnet waren. Sie wurden häufig bereits bei Neugeborenen festgestellt. Bei Kindern, die älter waren als 3 Monate und bei Erwachsenen lagen sie stets vor. — In den muskulären Arterien traten die verkalkten Anteile der inneren elastischen Membran makroskopisch als schwarze paarweise angeordnete „Kalkbänder” entlang den Rändern vorgebildeter Membranspalten auf. Bei ausgeprägter Calcinose konnte mit der angewandten Methode das gesamte Spaltensystem der inneren elastischen Membran dargestellt werden. Kalkbänder wurden in den muskulären Arterien der unteren Extremität bei allen 10–20 Jahre alten Verstorbenen vorgefunden und waren auch in den nachfolgenden Altersstufen stets vorhanden. Beim Zusammenfluß von Kalkbändern und polygonalen Kalkinkrustationen entstehen in der inneren elastischen Membran folienartige Kalkablagerungen („Kalkfolien”). Die Kalkbänder und Kalkfolien stellen Kristallisationspunkte für körnige Kalkablagerungen dar, die zumeist an ihrer äußeren, der Media zugekehrten Seite entstehen.
    Notes: Abstract Calcification patterns of the internal elastic membrane of the main pelvic arteries, lower limb arteries, brachial, splenic and renal arteries were demonstrated grossly by a modified von Kossa technique. In the elastic segment in the common and internal iliac arteries, the membrane calcification appeared as groups of roundish or polygonal incrustations. They were found frequently in newborns, and were always present in infants of more than three months, as well as in adults. In the muscular arteries, the calcified parts of the internal elastic membrane appeared grossly as pairs of bands (“calcific bands”) along the edges of the pre-existing gaps in this membrane. When calcification was pronounced, the whole pattern of the membrane gaps could be demonstrated by the method used in this study. Calcific bands were found in the muscular arteries of the lower limbs in all 10–20 year-old subjects, and were always present in the older age groups. The confluence of calcific bands or polygonal membrane incrustations found in the iliac arteries lead to sheet-like membrane calcification. The calcific bands and sheets represent crystallizing points for grain-like calcific deposits, which appear later on the medial surface.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 3 (1969), S. 363-365 
    ISSN: 1432-0827
    Keywords: Calcification ; Mitochondria ; Protozoa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 3 (1969), S. 38-54 
    ISSN: 1432-0827
    Keywords: Epiphyseal cartilage ; Calcification ; Apatite crystals ; Organic/Inorganic relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les rapports entre composants organiques et inorganiques du cartilage ont été étudiés au niveau des épiphyses tibiales chez des rats de 5 jours et au niveau des jonctions costo-chondrales chez des cobayes d'un mois. Voici les principaux résultats auxquels on est parvenu: (a) Dans les zones où la calcification s'amorce les cristallites d'apatite sont susceptibles d'être facilement éliminés des coupes en araldite et en glycol methacrylate (GMA) après traitement pendant une heure par une solution d'acide formique au 2%. (b) Les zones décalcifiées sont douées d'une faible densité aux électrons et vont exemptes d'une structure quelconque. Seulement la fixation à l'osmium peut révéler du matériel amorphe. (c) Indépendemment du fixateur et du moyen d'inclusion, les coupes décalcifiées, traitées par l'acétate d'uranyl et/ou par le citrate de plomb, montrent de fines structures allongées dont l'aspect est semblable à celui des cristallites. (d) Ces structures ainsi qu'un fond dense interposé prennent l'acide phosphotungstique (PTA) dans les coupes en GMA, une méthode celle-ci qui met en évidence les polysaccharides. (e) Le fond dense ne prend plus le PTA après traitement par la hyaluronidase et en même temps les structures semblables au cristallites apparaissent plus faibles. Après traitement par l'acétate d'uranyl et le citrate de plomb, l'attaque par la hyaluronidase ne produit aucune modification appréciable. Au contraire l'aspect des structures semblables aux cristallites apparait modifié par la digestion à la papaïne. (f) Quand la décalcification à l'EDTA précéde l'enrobage, des amas de matériel fibrillaire se mettent en évidence dans les zones où la calcification s'était amorcée. L'ensemble de ces résultats permet d'établir la nature organique des structures semblables au cristallites et porte aussi à admettre que celles-ci soient formées par de fins filaments cylindriques (digérés par la papaïne) entourés, et probablement engainés par del polysaccharides (digérés par la hyaluronidase et prennant le PTA dans les coupes en GMA).
    Abstract: Zusammenfassung Die Wechselbeziehungen zwischen den organischen und inorganischen Substanzen des verkalkenden Knorpels wurden in der tibialen und femuralen Epiphyse 5 Tage alter Ratten und in den Rippen 1 Monat alter Meerschweinchen untersucht. Die Hauptergebnisse waren: a) Die Hydroxyapatitkristalle der Frühverkalkungszonen können in Araldit- wie auch in Glycolmethylacrilatschnitten (GMA) mit einer lstündigen Behandlung durch 1% ige Ameisensäure leicht entfernt werden. b) Die entkalkten Zonen haben eine sehr niedrige Elektronendichte und enthalten keine sichtbaren Festkörper. Nach Fixierung mit Osmiumsäure kann man darin ein formloses Material erkennen. c) Eine Färbung der Schnitte mit Uranacetat und Bleicitrat, welche von den Fixier- und Einbettungsmitteln nicht beeinträchtigt wird, zeigt feine, längliche Körper (“Kristallgeister”) an, welche morphologisch den Kristallen von Hydroxyapatit gleichen. d) Die Färbung der GMA-Schnitte mit Phosphowolframsäure (PWS), eine Methode welche Polysaccharide anzeigt, hob diese “Kristallgeister” besonders hervor und demonstrierte auch eine dichte dazwischenliegende Grundsubstanz. e) Diese Substanz ist nach Behandlung mit Hyaluronidase nicht mehr färbbar mit PWS; die Färbbarkeit der “Kristallgeister” wird dabei jedoch nur verringert. Die Hyaluronidasebehandlung verändert die Uranacetat- und Bleicitratfärbung nicht. Die Feinstruktur der “Kristallgeister” wird durch Papainbehandlung sehr angegriffen. f) Falls die Schnitte vor dem Einbetten mit EDTA entkalkt werden, können Faserbündel in den Frühzonen der Verkalkung nachgewiesen werden. Diese Ergebnisse bestätigen die organische Natur der “Kristallgeister”. Sie beweisen auch, daß dieselben aus feinen Proteinstäbchen bestehen (verdaulich in Papain) und von Polysacchariden umgeben und vielleicht auch überzogen sind (verdaulich in Hyaluronidase und anfärbbar mit PWS).
    Notes: Abstract The organic/inorganic relationships in calcifying cartilage have been studied in tibialfemoral epiphyses of 5-day-old rats and in costochondral junctions of 1-month-old guinea pigs. The main results are: (a) Apatite crystallites in areas of early cartilage calcification are easily removed from araldite and glycol methacrylate (GMA) sections by 1-hour treatment with 2% formic acid. (b) The decalcified areas have a very low electron density and do not contain recognizable structures. Only after osmium fixation can an amorphous material be found in them. (c) Independently from the fixative and the embedding medium, staining decalcified areas with uranyl acetate and/or lead citrate reveals thin, elongated structures (crystallite ghosts) similar in shape to apatite crystallites. (d) These crystallite ghosts and a dense background are stained by phosphotungstic acid (PTA) in GMA sections, a method which reveals polysaccharides. (e) The dense background is no longer stained by PTA after hyaluronidase digestion and the stainability of the crystallite ghosts is reduced. After uranyl acetate/lead citrate staining there are no recognizable changes due to hyaluronidase. But, on the other hand, the fine structure of the crystallite ghosts is modified by papain digestion. (f) Clusters of fibrillar material are present in the areas of early calcification when EDTA decalcification is carried out before embedding the specimens. These results confirm the organic nature of the crystallite ghosts and suggest that they are formed by thin, rod-like protein/like structures (digested by papain) surrounded, and probably sheathed, by acid polysaccharides (digested by hyaluronidase and stained by PTA in GMA sections).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 4 (1969), S. 136-146 
    ISSN: 1432-0827
    Keywords: Bone ; Calcification ; Osteoblasts ; Osteoclasts ; Poultry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'activité des cellules osseuses et la composition du fémur de pondeuses furent examinées pendant sept jours de déficience calcique (diète contenant 0,13% de calcium) et sept jours de réplétion (diète contenant 3,2% de calcium). Du point de vue histologique, seul l'os cortical donnait des signes nets de résorption et d'activité ostéoclastique. Le nombre d'ostéoclastes dans l'os médullaire différait peu des valuers témoin pendant les périodes de déficience et de réplétion subséquente, sauf pour une augmentation significative au premier jour de déplétion. L'effect histologique le plus important dans l'os médullaire était une augmentation marquée en nombre d'ostéoblastes aux troisième, cinquième, et un peu moins au septième jours de déplétion. Le nombre d'ostéoblastes était en corrélation positive avec la teneur de l'os médullaire en ostéoide et négative avec son degré de calcification. L'activité de l'os médullaire en phosphatase alcaline augmentait avec la longueur de la déficience calcique. Un jour après le retour des pondeuses à une diète contenant 3,2% de calcium, la calcification de l'os médullaire avait augmenté de façon significative, le nombre d'ostéoblastes avait diminué au niveau ou au-dessous du niveau de contrôle et l'activité de la phosphatase alcaline avait baissé considérablement. L'importance de ces résultats est discutée par rapport au controle des populations des cellules dan l'os et au rôle de l'os médullaire.
    Abstract: Zusammenfassung Die Zahl der Knochenzellen und die Zusammensetzung des Femurs von Legehennen wurden während einer siebentägigen Calciumentzugsperiode (Calciumgehalt des Futters 0,13%) und einer siebentägigen Ersatzperiode (Calciumgehalt des Futters 3,2%) untersucht. Histologisch zeigte nur die Cortex eindeutige Knochenresorption und osteoklastische Aktivität. Abgesehen von einer signifikanten Zunahme am 1. Tag des Calciumentzuges, variierte die Zahl der Osteoklasten im Markknochen sowohl während der Entzugs- als auch während der nachfolgenden Ersatzperiode wenig. Die wichtigste histologische Änderung im Markknochen bestand in einer starken Zunahme in der Zahl der Osteoblasten am 3., 5. und etwas weniger am 7. Tag der Entzugsperiode. Die Zahl der Osteoblasten zeigte eine positive Korrelation mit dem Osteoidgehalt des Markknochens und eine negative mit dem Grade seiner Verkalkung. Die Aktivität der alkalischen Phosphatase im Markknochen war desto größer je länger den Hennen die calciumarme Ration verfüttert worden war. Die Wiederverabreichung der Ration, welche 3,2% Calcium enthielt, verursachte innerhalb eines Tages eine signifikante Zunahme in der Verkalkung des Markknochens, ein Absinken der Osteoblastzahl auf die Kontrollwerte oder unter sie und eine drastische Verringerung der alkalischen Phosphataseaktivität. Die Bedeutung dieser Ergebnisse in bezug auf die Kontrolle des Knochenzellenbestandes und auf die Funktion des Markknochens wird diskutiert.
    Notes: Abstract Bone cell activity and the composition of the femur of laying hens were studied during 7 days of calcium depletion on a 0.13% calcium diet and 7 days of calcium repletion on a 3.2% calcium diet. Histologically, only cortical bone showed clear signs of bone resorption and osteoclastic activity during the depletion period. The number of osteoclasts in medullary bone varied little from control values throughout both calcium depletion and repletion, except for a significant increase on the first day of depletion. The major histologicalchange in medullary bone was a marked increase in the number of osteoblasts on the third, fifth and, to a lesser extent, seventh, day of depletion. The number of osteoblasts in medullary bone was positively correlated with its osteoid content and negatively correlated with its degree of calcification. Alkaline phosphatase activity of medullary bone increased with the time the hens had been on the calcium-deficient diet. Returning the hens to the 3.2% calcium ration caused, within one day, a significant increase in medullary bone calcification, a decrease of osteoblast numbers to, or below, control levels, and a drastic reduction in alkaline phosphatase activity of medullary bone. The significance of these findings in relation to the control of bone cell populations and the functions of medullary bone is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 4 (1969), S. 101-112 
    ISSN: 1432-0827
    Keywords: Calcification ; Ligament ; Mollusc ; Aragonite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Une étude de microscopie électronique est réalisée sur la formation et la structure du ligament interne deMytilus edulis etPinctada radiata. Cette partie du ligament est dérivée des cellules isthmiques qui sont de forme cylindrique irrégulière. Elles présentent un ergastoplasme bien développé et un appareil de Golgi, engagé dans l'élaboration de vésicules et granules qui s'incorporent au niveau de la conchioline. Les cristaux se forment au niveau du front de calcification, à la surface interne du ligament. Ils sont entourés par une enveloppe. Ils se présentent comme des monocristaux d'aragonite, allongés et en forme d'aiguilles, dispersés dans le ligament. Bien que les constituants de la carapace et du ligament soient identiques, il existe des différences concernant l'augmentation quantitative de conchioline et une diminution en nombre, forme diverse, groupement et croissance des cristaux. Ces différences sont probablement liées à la fonction spécialisée du ligament.
    Abstract: Zusammenfassung Die Bildung und Struktur des inneren Ligamentes vonMytilus edulis undPinctada radiata wurden am Elektronenmikroskop untersucht. Dieser Teil des Ligamentes stammt von den Isthmuszellen ab, deren Form unregelmäßig säulenartig ist. Sie zeigen ein vorspringendes, rauhes endoplasmatisches Reticulum und einen Golgiapparat, welche sich mit der Bildung von Bläschen und Granula befassen, die schließlich in einem integralen Teil des Conchiolins eingebaut werden. Die Kristalle entstehen an der Calcifikationsgrenze an der inneren Oberfläche des Ligamentes und sind in Hüllen eingeschlossen. Sie bestehen aus langen, nadelförmigen, einzelnen Aragonit-Kristallen, die über das ganze Ligament verteilt sind. Obschon die Bestandteile der Muschel und des Ligamentes gleichartig sind, unterscheiden sich die beiden durch eine erhöhte conchiolinmenge, wie auch durch eine Abnahme der Anzahl der Kristalle, welche verschieden in der Form, in der Anordnung und im Wachstum sind. Dies alles ist vermutlich auf die spezielle Funktion des Ligamentes zurückzuführen.
    Notes: Abstract An electron microscope study was made of the formation and structure of the inner ligament ofMytilus edulis andPinctada radiata. This part of the ligament is derived from the isthmus cells which are irregular columnar in shape. They exhibit a prominent rough endoplasmic reticulum and a Golgi apparatus, which are concerned with the elaboration of vesicles and granules eventually incorporated into an integral part of the conchiolin. The crystals arise at the calcification front at the inner surface of the ligament and are enclosed in envelopes. They consist of long, needle-shaped, single aragonite crystals widely dispersed in the ligament. Although the components of the shell and ligament are similar, differences between them consist of an increased amount of conchiolin, as well as a decrease in the amount, diversity of form, arrangement and growth of the crystals; all probably related to the specialized function of the ligament.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 4 (1969), S. 359-365 
    ISSN: 1432-0827
    Keywords: Metals ; Ions ; Buffers ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'action de divers ions métalliques polyvalents sur les propriétés métastables d'un tampon calcifiable a été étudiée. A des concentrations de 1 μM ou moins, les ions Pb2+, F2+, Fe3+, Cr3+, Bi3+ et Al3+ déstabilisent le tampon. Il semble que les phosphates insolubles formés par ces ions déclanchent la précipitation de l'apatite. L'importance de ces résultats dans l'étiologie des calcifications pathologiques et la calciphylaxie est décrite.
    Abstract: Zusammenfassung Die Wirkung von verschiedenen polyvalenten Metallionen auf die Metastabilität eines Calcifikationspuffers wurde untersucht. Bei Konzentrationen von 1 μM oder weniger wird der Puffer durch Pb2+, Fe2+, Fe2+, Cr3+, Bi3+ und Al3+ entstabilisiert. Die Resultate lassen vermuten, daß unlösliche Phosphate, die mit diesen Ionen entstehen, eine Fällung von Apatit veranlassen. Die Bedeutung dieser Befunde bei pathologischen Verkalkungen und Calciphylaxis werden besprochen.
    Notes: Abstract The effect was studied of various polyvalent metal ions on the metastability of a calcification buffer. At concentration of 1 μM or less, Pb2+, Fe2+, Fe3+, Cr3+, Bi3+ and Al3+ ions were found to destabilize the buffer. The results suggest that insoluble phosphates formed by these ions initiate the precipitation of calcium apatite. The implications of these findings to pathological calcification and calciphylaxis are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 4 (1969), S. 39-47 
    ISSN: 1432-0827
    Keywords: Dehydroepiandrosterone ; Calcification ; Embryo ; Tissue Culture ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les modes d'utilisation de glucose, le contenu de calcium et d'hydroxyproline et la densité cellulaire du perioste de les os frontaux d'embryons de poulet de 12 et 13 jours de developpement, cultivés sur coagulum de plasma, se presentant différenment à chaque âge. Cultivés avec sulfate de déhydroèpiandrostérone en concentration 1 mM, les frontaux de 12 jours montrent un synthese augmentée du matrice osseuse, celle de 13 jours se calcifient à une vélocité significativement plus grande que celle des os contôles. Le degré de calcification au quatrième jour de culture measuré par la relation calcium/hydroxyproline, suit un fonction lineáire avec le logarithme des doses de sulfate de dehydroepiandrostérone employées (0.5, 1,0 et 2,0 mM). Les renseignements obtenus indiquent que les frontaux de 13 jours, cultivés “in vitro” constituent modeles experimentaux appropriés pour étudier l'effet des androgénes sur le tissue osseux.
    Abstract: Zusammenfassung Stirnbeine von Hühnerembryonen an ihrem 12. und 13. Entwicklungstag entnommen und in vitro kultiviert zeigen verschiedene Arten der Glucoseverwertung der Periostzellendichte, des Calcium- und Hydroxyprolingehaltes. Wird Dehydroepiandrosteronsulfat dem Medium in einer 1 mM-Konzentration zugegeben, so beteiligen sich die 12tägigen Stirnbeine vorwiegend an der Knochengewebesynthese, während die 13tägigen signifikant stärker verkalken als die Kontrollen. Gemessen an der Calcium/hydroxyprolin Ratio bildet die Verkalkung der 13tägigen Stirnbeine eine lineare Funktion mit den Logarithmen der verwendeten Dosen von Dehydroepiandrosteronsulfat (0,5, 1,0 und 2,0 mM). Das in vitro kultivierte 13tägige Stirnbein schein ein geeignetes Experimentiermodell zur Studie der Dehydroepiandrosteronsulfatwirkung auf das Knochengewebe zu sein, weil es das grundlegende Phänomen (erhöhte Verkalkung) wiedergibt, welches man auch bei mit Androgenen behandelten Menschen und Tieren beobachtet.
    Notes: Abstract Chick embryo frontal bones at 12 and 13 days of development cultivatedin vitro exhibit different patterns of glucose utilization, periosteal cellular density and calcium and hydroxyproline content. When dehydroepiandrosterone sulfate is added to the medium at a concentration 1 mM, 12-day frontals engage primarily in osteoid tissue synthesis while 13-day frontals calcify at a significantly greater rate than controls. Measured with the ratio calcium/hydroxyproline, the calcification of 13-day frontals follows a linear function with the logarithm of the doses of dehydroepiandrosterone sulfate employed (0.5, 1.0 and 2.0 mM). The 13-day frontal bone cultivatedin vitro seems to be an adequate experimental model for the study of the effects of dehydroepiandrosterone sulfate on bone tissue because it reproduces the basic phenomenon (increased calcification) observed in man and animals treated with androgens.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 56 (1995), S. 140-144 
    ISSN: 1432-0827
    Keywords: Bone sialoprotein ; Collagen ; Hole zone ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Bone sialoprotein (BSP) has an affinity to collagen fibrils [25]. A role of carbohydrate chains in the affinity was examined by removing sialic acids of BSP. Neuraminidase treatment of the BSP increased the binding to collagen. Binding sites of BSP on collagen were examined by biochemical and electron-microscopic methods. Purified bovine BSP was labeled with biotin. Collagen α chains or CNBr peptides were separated by electrophoresis and transfered to nitrocellulose membranes. The membranes were incubated with the biotin-labeled BSP, and the bound BSP was visualized with avidin conjugated with alkaline phosphatase. The labeled BSP was preferentially bound to the α 2 chain, and peptides derived from α 2 chain. In another experiment, the labeled BSP was incubated with reconstituted native collagen fibrils. The mixture was put on a copper grid, reacted with avidin conjugated with gold particles, and observed with an electron microscope. The gold particles were seen mainly within hole zones of the fibrils. BSP bound to the α 2 chain within the hole zones may regulate the onset of calcification at hole zones and the cell binding to collagen fibrils.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 2 (1968), S. 1-19 
    ISSN: 1432-0827
    Keywords: Collagen ; Hydroxyapatite ; Keratin ; Enamel ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 2 (1968), S. 60-66 
    ISSN: 1432-0827
    Keywords: Fluorides ; Topical/Pharmacodynamics ; Penicillin/Pharmacodynamics ; Calcification ; Physiologic/Drug Effects ; Rats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé L'objet de ce travail était de comparer le phénomène de la maturation postéruptive dans les molaires des rats ordinaires et sans germes à qui on a donné à manger un régime «non-cariogène». On a étudié les effets de l'application topique du fluorure et de la nourriture de la penicilline sur la maturation. Les molaires des rats ordinaires (nourris d'un régime «chow» — aliment mixte pour les animaux préparé d'habitude sous la forme d'une farine ou en boulettes) traités topiquement avec une solution à 1% de NaF et les molaires des rats ordinaires nourris d'un régime «chow» complété avec la penicilline à 1% ont montré un degré de maturation significativement plus grand que les molaires des rats de la même portée nourris de «chow» et traités avec de l'eau. De l'autre côté, les molaires des rats sans germes traités topiquement avec une solution à 1% de NaF n'ont montré aucune différence significative dans le degré de maturation des molaires de rats de contrôle semblables traités topiqument avec l'eau. Ces résultats sont en accord avec l'hypothèse que dans un milieu normal le procédé de minéralisation (maturation) est opposé par un procédé de déminéralisation. Le procédé de déminéralisation est un résultat de la production d'acide par des bactéries qui métabolisent les aliments encastrés dans les «sulci» des molaires. On propose que dans les animaux ordinaires le fluorure et la penicilline peuvent influencer la maturation en empêchant le procédé de déminéralisation. Dans les animaux sans germes le procédé de déminéralisation est absent parce que la microflore orale est absente.
    Abstract: Zusammenfassung Der Zweck dieser Arbeit war ein Vergleich des nach dem Durchbruch auftretenden Reifungsphänomens der Backenzähne von gewöhnlich und von keimfrei gehaltenen Ratten, die mit einer nicht-cariogenen Diät ernährt wurden. Es wurden die Auswirkungen von topisch angewendetem Fluorid, verbunden mit Penicillin-Fütterung auf die Reifung untersucht. Die Backenzähne der gewöhnlich gehaltenen Ratten (mit “Chow”-Diät ernährt), die mit einer 1%igen Na-Fluoridlösung topisch behandelt wurden, und solchen deren “Chow”-Diät zu 1% mit Penicillin versetzt wurde, zeigten einen erheblich größeren Reifungsgrad als die Backenzähne von Tieren des gleichen Wurfes, die nur mit der “Chow”-Diät und Wasser ernährt wurden. Diese Resultate stimmen mit der Hypothese überein, daß in einer normalen Umgebung dem Mineralisationsprozeß (Reifung) ein Demineralisationsprozeß entgegenwirkt. Der Demineralisationsprozeß ist durch eine Säureproduktion von Bakterien bedingt, welche die in die Zahnfurchen eingepreßten Nahrungsbestandteile metabolisieren. Es wird die Annahme vorgeschlagen, daß Fluoride und Penicillin bei den gewöhnlich gehaltenen Tieren die Reifung durch eine Inhibition des Demineralisationsprozesses beeinflussen. Bei keimfrei gehaltenen Tieren findet dagegen kein Demineralisationsprozeß statt, da die orale Mikroflora fehlt.
    Notes: Abstract The purpose of this work was to compare the phenomenon of post-eruptive maturation in molars of conventional and germfree rats fed non-cariogenic diets. The effects of topical application of fluoride and feeding penicillin on maturation were studied. The molars of conventional rats (fed a chow diet) treated topically with a 1% NaF solution and the molars of conventional rats fed a chow diet supplemented with 1% penicillin showed a significantly greater degree of maturation than did the molars of littermate rats fed chow and treated with water. On the other hand, the molars of germfree rats treated topically with a 1% NaF solution showed no significant difference in degree of maturation from the molars of similar control rats topically treated with water. These data are consistent with an hypothesis that in a normal environment the mineralization (maturation) process is opposed by a demineralization process. The demineralization process is a result of production of acid by bacteria metabolizing the diet impacted in the sulci of molars. It is proposed that in conventional animals fluoride and penicillin may influence maturation by inhibiting the demineralization process. In the germfree animals the demineralization process is absent because the oral microflora is absent.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 2 (1968), S. 361-369 
    ISSN: 1432-0827
    Keywords: Calcification ; Hydroxyapatite ; Keratin ; Hair ; Electron diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Certaines régions du cortex des fibres de kératine contiennent une proportion relativement élevée de matériel non kératinisé. L'orientation microfibrillaire dans ces régions est biaxiale et on y trouve, en outre, des zones de matériel amorphe. Les sels calciques, et en particulier l'hydroxyleapatite, sont étudiés par diffraction électronique qui permet de les localiser et de les identifier. En outre, cette technique permet de déterminer la fréquence de cellules nonkératinisées dans la partie interne du cortex et de les comparer avec les propriétés histochimiques de cette région. Une comparison est effectuée entre la calcification de la kératine et celle intéressant le collagène et l'élastine.
    Abstract: Zusammenfassung Es wird gezeigt, daß Bereiche im Cortex von gewissen Keratinfasern einen relativ hohen Anteil an nichtkeratinösem Material enthalten. Ferner konnte nachgewiesen werden, daß die Orientierung der Mikrofibrillen in diesen Bereichen biaxialer Art ist, und daß Bezirke von amorphem Material vorhanden sind. Die Calciumsalze und insbesondere das Hydroxyapatit konnten mit Hilfe der Elektronendiffraktion lokalisiert und identifiziert werden. Diese Methode hat sich auch als wertvoll erwiesen, um die Wechselbeziehung zwischen dem Vorkommen von einigen nichtkeratinisierten Zellen im Cortexinnern und den histochemischen Eigenschaften dieser Regionen zu zeigen. Ein Vergleich wird gemacht zwischen der Umgebung der Verkalkungsstellen im Keratin mit derjenigen im Kollagen und im Elastin.
    Notes: Abstract Regions in the cortex of some keratin fibres are shown to contain a relatively high proportion of non-keratinous material. The microfibrillar orientation in these regions is shown to be biaxial in nature and, in addition, areas of amorphous material are reported. Calcium salts, in particular hydroxyapatite, have been located and identified using electron diffraction, which has also proved valuable in correlating the incidence of some non-keratinised cells in the inner part of the cortex with the histochemical properties of this region. A comparison is made between the environment of the sites of calcification in keratin with those in collagen and elastin.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 2 (1968), S. 214-228 
    ISSN: 1432-0827
    Keywords: Calcinosis ; Calcification ; Cartilage ; Collagen ; Mineral metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les facteurs, influençant la vitesse et l'intensité du phénomène d'association des ions calcium et phosphates avec des fibres contenant du collagène, et préparés à partir du tendon de boeuf par deux méthodes d'extraction différentes, ont été étudiés. Les fibres, obtenues par ces deux méthodes, nécessitent spécifiquement du phosphate pour absorber du calcium et vice versa. L'absorption ionique des deux préparations est inhibée par du Mg++, du pyrophosphate et un peptide acidique, isolé du sérum humain. Alors que les fibres contenant du collagène, préparées selon les deux méthodes, présentent une absorption ionique à des vitesses sensiblement identiques, seule une des méthodes donne une matrice réagissant positivement à la technique de coloration au nitrate d'argent de von Kossa. Etant donné que les deux critères de calcification sont intéressés de façon identique par des conditions de réaction et par des inhibiteurs, il apparait que les deux facteurs sont des manifestations de différents stades de calcification et que des études d'absorption ionique fournissent une base quantitative d'appréciation de la calcification, pouvant être d'importance pour l'étude du mécanisme et de contrôle de la minéralisation tissulaire.
    Abstract: Zusammenfassung Überprüft wurden die Faktoren, welche Geschwindigkeit und Ausmaß der Erscheinung beeinflussen, wobei Calcium- und Phosphationen sich mit den kollagenhaltigen, durch zwei verschiedene Extraktionsmethoden aus Rindersehnen gewonnenen Fasern eng zusammenbinden. Die mit beiden Methoden zubereiteten Fasern benötigen spezifisch Phosphat für die Calciumaufnahme und Calcium für die Phosphataufnahme. Die Ionenaufnahme beider Arten wird durch Mg++, Pyrophosphat und saure, aus dem menschlichen Serum isolierte Peptide gehemmt. Während die nach beiden Methoden präparierten kollagenhaltigen Fasern eine Ionenaufnahme von beinahe gleicher Geschwindigkeit verursachen, ergibt nur eine dieser Methoden eine Matrix, die mit der Silbernitratfärbung nach vonKossa positiv reagiert. Da beide Calcifikationskriterien gleicherweise durch Reaktionsbedingungen und Inhibitoren beeinflußt werden, wird daraus geschlossen, daß beide Erscheinungen verschiedener Stadien des Gesamtcalcifikationsprozesses sind. Untersuchungen über die Ionenaufnahme ergeben eine quantitative Angabe der Verkalkung, welche für die Erforschung des Mechanismus und der Kontrolle der Mineralisation der Gewebe wichtig sein könnte.
    Notes: Abstract Factors that influence the rate and extent of the phenomenon in which calcium and phosphate ions become firmly associated with collagen-containing fibers prepared from beef tendon by two different extraction methods have been investigated. The fibers produced by both methods specifically require phosphate for calcium uptake and calcium is required for phosphate uptake. Ion uptake by both types is inhibited by Mg++, pyrophosphate, and an acidic peptide isolated from human serum. Whereas the collagen-containing fibers prepared by both methods induce ion uptake at nearly identical rates, only one of the methods produced a matrix that gives a positive response to the silver nitrate staining technique of von Kossa. Since both criteria of calcification are similarly influenced by reaction conditions and inhibitors, it is concluded that both are manifestations of different stages of the overall calcification process and that studies of ion uptake provide a quantitative assessment of calcification which could be of importance for investigating the mechanism and control of tissue mineralization.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 56 (1995), S. 403-407 
    ISSN: 1432-0827
    Keywords: Bone sialoprotein ; Fibronectin ; Type I colfagen ; MC3T3-E1 cells ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Bone sialoprotein (BSP) containing an Arg-Gly-Asp cell-binding sequence was purified from bovine bone 4 M guanidine-HCl extract after HCl demineralization by a series of chromatographic procedures. When this protein was coated on culture dishes in the presence of type I collagen, it increased both DNA content and alkaline phosphatase (ALP) activity in osteoblast-like MC3T3-E1 cells, and stimulated calcification in the cells, whereas fibronectin, another cell-binding protein, showed a marked increase in the DNA content but had little effect on the ALP activity. These findings suggest that BSP is mitogenic for preosteoblasts and differentiating the cells into osteoblasts, thereby stimulating bone calcification
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 99-101 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; High temperature open-tubular columns ; Solvent make-up ; Acetophenone oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Acetophnone, a substance stable at room temperature, is readily oxidizes in a high temperature open tubular liquid chromatographic system by the residual oxygen in the mobile phase. The oxidation product is less UV absorptive and detection sensitivity decreases greatly. To prevent the oxidation, through degassing of the mobile phase is necessary.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Endotoxins ; Lipopolysaccharide ; Aminated poly(γ-methyl L-glutamate) ; Bovine serum albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the selective removal of endotoxins from various protein solutions using columns packed with aminated poly (γ-methyl L-glutamate) (PMLG-NH2) spheres. The PMLG-NH2 adsorbents showed a high adsorbing activity for endotoxins which had an ionic strength of μ=0.05–1.0 and pH 5.0–9.0. The endotoxin-adsorbing capacity per millitre of the wet adsorbent increased from 0.40 to 1.35 mg (E. coli O111: B4 LPS) at μ=0.2 and pH 7.0 while the aminogroup content of the adsorbent increased from 0.8 to 3.5 meq g−1. The PMLG-NH2-3.5 has an amino-group content of 3.5 meq g−1. This column packing selectively adsorbed endotoxins, without loss of the protein, from a γ-globulin or cytochromec solution which contained endotoxins at μ=0.05 and pH 7.0. On the other hand, when bovine serum albumin (BSA) was present in solution with endotoxins, both the endotoxins and the BSA were adsorbed by the column. The BSA-adsorbing activity increased with increasing amino-group content of the adsorbent. However, this undesirable adsorption was suppressed with increasing ionic strength of the buffer. As a result, when the packing which had an amino-group content of 1.5 meg g−1 was used in conditions of μ=0.2 and pH 7.0, the endotoxins were removed from a BSA-containing solution without affecting the recovery of the BSA.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 51-57 
    ISSN: 1612-1112
    Keywords: Column electrophoresis ; Column liquid chromatography ; Phenolic lignin degradation compounds ; Sugar degradation products ; Quantitative analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the quantitative analysis of phenolic lignin degradation products by capillary electrophoresis (CE) with on-column UV detection has been developed. The liquid biomass solutions contain low molecular hemicellulosic sugars and phenolic lignin degradation products with various degrees of polymerization. Special attention has been paid to the monomeric phenolic components of lignin degradation fragments, e.g. derivatives of phenolic acids, aldehydes, and alcohols. Uncoated fused silica capillaries and borate-phosphate buffer systems at moderate pH conditions were used in order to separate the compounds of interest. To provide validation of the method, the same samples were analyzed independently by HPLC using gradient elution on a RP-C18 column. As sugar degradation fragment, furan-2-carboxylic acid was detected.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 85-90 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenolic compounds ; Ion-pair solid phase extraction ; On-line trace enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two packing materials, C18 and PLRP-S, are studied for on-line trace enrichment of phenolic compounds in water. Various precolumns of different internal diameter are also tested and the addition of an ion-pair reagent to increase retention and thus, breakthrough volumes of phenolic compounds, is studied. Best results are obtained when a PLRP-S precolumn is coupled on-line with a C18 analytical column and DAD detector. Addition of TBA considerably increases breakthrough volumes. In contrast, when a C18 precolumn is used, breakthrough volumes are lower and it is impossible to determine TCP and PCP, under the experimental conditions used, because of interference of other nonpolar compounds in the samples. The performance of the system is evaluated with river and tap water and the preconcentration of 10 ml of sample in a PLRP-S precolumn involves a linear range between 1 μg 1−1 and 20 μl−1 and limits of determination between 0.5 μg l−1 and 1 μg l−1 are obtained.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 631-637 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Trace analysis ; Pesticides in tap water ; Aromatic sulphonates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Methodology and instrumentation are described which allow chromatographic screening of water samples under substantially simplified conditions and at reduced cost. A single column is used to accomplish sample extraction, trace enrichment, and separation. The performance of such a system is demonstrated, and the results compared with conventionally used concepts.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Transchelation ; Zinc pyrithione and related compounds ; Antidandruff formulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An analytical procedure has been developed for the determination of zinc pyrithione in antidandruff formulations. Zinc pyrithione was converted into a stable copper complex and then analysed by reversed-phase HPLC. The proposed method allows the separation of the analyte from related pyrithiones and therefore is able to verify the compliance of cosmetic preparations with current legislation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Benzodiazepines ; Solvent effects ; ACN clusters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two different methods were used to determine the separation factor α at different temperatures and the Gibbs-Helmholtz parameters (Δ(ΔH), Δ(ΔS)) of two adjacent benzodiazepines on a chromatogram were obtained from plots of lnα versus 1/T. We first studied each factor (fraction of water ϕ in the ACN/water mixture and column temperatureT), which controls the retention mechanism, and then we examined the simultaneous variation of all these factors. The changes in Δ(ΔH) and Δ(ΔS) in relation to a volume fraction of water ϕ in an ACN/water mixture were examined. In the ACN/water system, Δ(ΔH) was fairly constant in the acetonitrile region of ϕ≤0.52 and appears to be a roughly linear function of ϕ for ϕ≥0.52. In this system Δ(ΔS) is approximately a parabolic function of ϕ with an optimum at ϕ≅0.52. The retention mechanism of ten benzodiazepines was found to be significantly different in the methanol/water and ACN/water mixtures. The separation optimization of these ten benzodiazepines was then considered. A fraction of water of 0.43 in the ACN/water mixture and a column temperature of 44°C gave the most efficient separation conditions in the ACN/water mixture.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyurethane degradation products ; 2,4- and 2,6-toluendiamine ; Urine analysis ; Breast implants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase HPLC method has been developed for the urinary determination of mutagenic 2,4- and 2,6-toluendiamines. These amines are degradation products of polyurethane, a material used to cover textured silicone breast implants. FMOC-Cl was used as fluorescent derivatising agent in order to obtain a limit of detection of 15 ng/ml in urine. Pre-treatment of urine samples was by liquid/liquid extraction and urine specimens of patients after surgury were analysed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 41 (1995), S. 657-660 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyphenols ; Flavonoids ; Phenolic acids and aldehydes ; Eucalyptus spp.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Standards of the polyphenols occurring in wood, bark and leaf extracts ofEucalyptus spp. (i.e. flavonoids and phenolic acids and aldehydes) have been analyzed by HPLC using reversed phase columns, gradient elution and diode-array detection. The conditions used are reported.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 657-661 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phases ; Polyencapsulated silica ; Polyacrylates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By copolymerization of silica modified with vinyl groups and acrylic acid esters in suspension highly efficient, polymeric-encapsulated stationary-phases can be prepared. The suspending liquid has to be selected such that the monomers are at least partially adsorbed on the surface and the polymer formed does not precipitate. Under these conditions stationary phases capable of speedy mass transfer can be prepared, where the reduced plate heights are between 2 and 3. The silica surface shielding is optimized so that basic and acidic solutes elute with symmetrical peak.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral resolution of amino acids ; Pre-column derivatization ; Fluorescent chiral tagging reagents ; Stereochemical purity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Derivatization of amino acid enantiomers with fluorescent chiral Edman-type reagents, 4-(3-isothiocyanatopyrrolidin-1-yl)-7-nitro-2,1,3-benzoxadiazole [R(−)- and S(+)-NBD-PyNCS] and 4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole [R(−)-and S(+)-DBD-PyNCS], yields corresponding diastereomers separable by reversed-phase HPLC on normal achiral columns. The resolved diastereomers were detected fluorometrically at 530 nm with excitation at 490 nm for the NBD-PyNCS derivatives and at 560 nm with excitation at 450 nm for those derived from DBD-PyNCS reagents. This HPLC-derivatization method was used for evaluation of stereochemical purity for some synthetic commercial peptides. The enantioanalysis was reliable down to 0.05% racemization of the amino acid residues and a quantity of 100 μg peptide sample was usually enough for the analysis. Two acid hydrolysis methods, i.e. the standard procedure with constant-boiling hydrochloric acid (HCl) and a rapid vapor-phase procedure with HCl-trifluoroacetic acid (TFA) mixture, were compared. The later was found to be unsuitable owing to increased racemization of the amino acid residues during the hydrolysis. Judging from the results obtained for proline and leucine residues, most of the tested peptides including biologically active peptides, such as neurotensin, [d-Ala2,d-Leu5]-enkepharin and morphine tolerance peptide, possessed stereochemical purities higher than 98%. Influence of structural features of the peptides on the racemization of the amino acid residues was found to be significant.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mass spectrometric detection ; Fast atom bombardment ionization ; Serum bile acid ; Rat bile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to analyse bile acids in biological matrices, e.g. rat bile and human serum, high performance liquid chromatography (HPLC) was coupled to continuous-flow fast atom bombardment mass spectrometry (CFFAB-MS). A gradient elution system which had already proved to be well suited for the quantitative determination of conjugated bile acids in bile was modified to allow HPLC-CFFAB-MS-coupling. Due to the sensitivity of this coupling method it is possible to obtain more information about the biliary bile acid pattern and species-specific secondary bile acids. Furthermore, we were able to identify obviously unknown bile acid species in rat bile which most likely classify as mono-oxo and di-oxo-taurocholates (MW 513 Da, 511 Da) and mono-oxo-glycocholates (MW 463 Da). In the present study we show that using this system it is possible to determine both conjugated and unconjugated as well as sulfated bile acids, without time consuming group separation and derivatization, from rat bile and human serum. In addition, it is suggested that the method presented here should be considered for use in routine analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fluorescence enhancement ; Bovine serum albumin ; Dansylamino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effects of acetonitrile and bovine serum albumin (BSA) concentrations on the signal intensity and retention behavior of dansylamino acids have been examined by using γ-cyclodextrin-bonded silica gel as the stationary phase in microcolumn liquid chromatography. Fluorescence intensities of dansylamino acids were enhanced by BSA as a mobile phase additive, e.g., detection limits of dansyl derivatives of L-Ala and L-Phe were improved by a factor of 12–18.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid phases ; Octanol-water partition coefficient ; Benzene and naphthalene derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown that the logarithm of the capacity factor (log k′) for fifteen benzene and naphthalene derivatives in micellar liquid chromatography with forty nine different mobile phases generally correlates better with the logarithm of the octanol-water partition coefficient (log Pow) than the capacity factor (k′). Optimum conditions are established to obtain the best linear correlations of log k′-log Pow.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Photolysis ; Electrochemical detection ; Drugs with chlorinated aromatic rings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Pharmaceuticals containing a thiazide ring or chlorinated aromatic ring were investigated with respect to enhanced selectivity in determination. Oxidative electrochemical detection coupled with HPLC was used to study the influence of the pH of the mobile phase under conditions of photolysis. To cover a pH range 3.9–12, the employment of a polymer column stable in alkaline media was necessary. The method offers the great advantage of derivatization without chemicals at low operating potentials, thereby providing high selectivity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 296-302 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Structural isomer separation ; Cyclodextrin ; Polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several β-cyclodextrin (CD)-bonded stationary phases for high performance liquid chromatography (HPLC) were prepared, based on silica beads coated with a poly(alkylamine), [poly(ethyleneimine)(PEI)]. In order to obtain stationary phases with a high content of CD and maximum accessibility of the CD cavity, the functionalization was carried out after the coating, using the mono-tosyl derivative of CD as the intermediate. The ability of these supports to separate ortho, meta and para isomers of some disubstituted benzene derivatives was examined. The contribution of the amino groups of the polymer and of the CD cavity to the separation process is discussed. The resolution is mainly based on the difference in the stability of the complexes of the various isomers with CD. The influence of the amount of CD on the height of the theoretical plate is also studied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Polystyrene ; Pellicular ; Ultra high molecular mass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ultra high molecular mass (〉 7 million dalton) polystyrenes are prone to degradation in size exclusion chromatography. In gradient elution reversed phase HPLC they do not elute visibly on small particle size porous supports. However, large diameter C18 pellicular particles were successfully employed for reversed phase study of ultra high molecular mass (15 million dalton) polystyrenes without polymer degradation during elution. Although retention for the lower molecular mass polystyrenes was lower than on small diameter porous particles, the medium high molecular mass polystyrenes (0.5–1 million dalton) showed similar retention. The addition of small diameter porous particles in small quantities, to the large diameter pellicular particles, increased the amount of retention of the low molecular mass polystyrenes without affecting the higher molecular mass polystyrenes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Methyl ethyl ketone in urine ; Derivatization ; 3-Methyl-2-benzothiazolinone hydrazone ; Comparison with GC-MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A HPLC method for the determination of methyl ethyl ketone (MEK) in urine after derivatization with 3-methyl-2-benzothiazolinone hydrazone is proposed. The calibration curve for the ketone was linear, ranging between 0.23–10 mg/L, with a detection limit of 0.025 mg/L. The results were compared to those obtained by GC-MS, coupled to the headspace technique. MEK derivatization and the derivative purification processes were verified with respect to the main variables such as reaction temperature, reagent concentration, probable interferences and enrichment phase. The method is simple and reliable and shows a good sensitivity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 382-386 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sulfonamides in foodstuffs ; Honey ; Milk ; Eggs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure for the simultaneous determination of several sulfonamides in different foods, such as honey, milk and eggs is proposed. The analysis is carried out using reversed phase liquid chromatography with spectrophotometric detection. Optimization of the mobile phase led to good separation and a short analysis time when an initial isocratic step with a 3∶97 acetonitrile: water mixture was used for 5 minutes, followed by a linear gradient up to a 40∶60 mixture over 15 min. The proposed method is suitable for routine quality control analysis to ensure the absence of sulfonamides in foods. Recovery studies yielded good results for all food samples because there were no interferences from the matrices.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 411-416 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Particle beam LC/MS interface ; Capillary columns for LC ; Mycotoxins ; Peanut meal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method for the analysis of aflatoxins in food extracts, based on liquid chromatography/mass spectrometry interfacing, is presented. The chromatographic separation was performed with a reversed phase packed capillary column coupled with a modified particle beam interface capable of handling microliter per minute flow rates. This system allows higher overall sensitivity and easier operation procedures. The method has proved to be particularly suitable for the analysis of the toxins in very complex matrices. The specificity of electron impact ionization allowed positive identification of the aflatoxins with an excellent response linearity for accurate quantitation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Reversed phase ; 2-benzoylbenzoic acids ; Anionic and cationic counter ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The 2-benzoylbenzoic acid series was investigated by reversed-phase, high-performance, thin-layer and column chromatography using various alkylammonium salts and di(2-ethylhexyl)orthophosphoric acid as polar associating reagents. The effects of the individual substituents on retention were quantified by Δlog k′ and ΔRM values. The compounds investigated differing in molecular structure (hydrophilic and hydrophobic substituents) commonly occurring groups in drugs and biologically active substances provide information on molecular interaction in these ion-pair systems. The combined effects on retention of organic modifier and ion-pair reagent concentration were investigated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Two-dimensional separation ; D- and L-amino acids ; Enantioseperation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A two-dimensional, column liquid chromatographic system is used for the determination of the D- and L-enantiomers of amino acids in biological samples. Separation of the amino acids is first on ion-exchange column by gradient elution with a sodium citratesodium chloride buffer. Enantioseparation is by subsequent injection of 3 μl heart-cuts of the individual amino acids onto a second column with a chiral crown ether stationary phase. Finally, fluorescence detection is after post-column labelling of the amino acids using ano-phthalaldehyde-2-mercaptoethanol reagent solution. The high separation power and selectivity of the system allow processing of complex samples with hardly any additional treatment and the determination of small quantities of D-amino acids in the presence of excess L-form. Applicability of the system is illustrated by the determination of D- and L-aspartate, serine, glutamate and alanine in various complex biological samples, such as protein hydrolysates, urine and biotechnological and food samples. Data are given on detectability, repeatability and linearity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion pair LC ; Sweeteners, preservatives and antioxidants ; Food additive analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A paired-ion, reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of sweeteners (dulcin, saccharin-Na and acesulfame-K), preservatives (sodium dehydroacetate, sorbic acid, salicyclic acid, benzoic acid, succinic acid, methyl-para-hydroxybenzoic acid, ethylpara-hydroxybenzoic acid, n-propyl-para-hydroxybenzoic acid, isopropyl-para-hydroxybenzoic acid, n-butyl-para-hydroxybenzoic acid, and isobutyl-para-hydroxybenzoic acid), and antioxidants (3-tertiary-butyl-4-hydroxyanisole and tertiary-butyl-hydroquinone). A mobile phase of acetonitrile-50 mM aqueous α-hydroxy-isobutyric acid solution (pH 4.5) (2.2 ∶ 3.4 or 2.4 ∶ 3.6, v/v) containing 2.5 mM hexadecyltrimethylammonium bromide and a C18 column with a flow rate at 1.0 mL/min and detection at 233 nm were used. This method was found to be very reproducible with detection limits ranged from 0.15 to 3.00 μg. The retention factor (k) of each additive could be affected by concentrations of hexadecyltrimethylammonium bromide and α-hydroxyisobutyric acid, and pH and ratio of mobile phase. The presence of additives in some food samples was determined.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Limit of detection ; Precision ; Uncertainty prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The precision of integration over noisy instrumental output for quantitative analysis is studied. A probability theory is developed to predict the relative standard deviation (RSD) of integration results over an integration domain from one-point integation (peak height measurement) to entire area integration in HPLC. Common integration modes of horizontal zero line and oblique zero line are taken into account, but no peak overlap is assumed. The question of the analytical superiority of peak height measurement or integration for quantitation is answered. In the HPLC apparatus used, the minimum RSD of measurements is found in the integration domain of ca. ±0.5 σ for analytes [peaks are approximated by the Gaussian signal of width, σ (standard deviation)]. The RSD of integration measurements is also shown to depend on the stochastic properties of back-ground noise (uncorrelated noise and correlated 1/f type noise). The theoretical conclusion is verified by Monte Carlo simulation and HPLC experiments for some aromatic compounds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair and GPC separations ; Amoxicillin oligomers ; β-Lactam ring polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polymeric substances formed from concentrated sodium amoxicillin in an aqueous solution have been separated using two high-performance liquid chromatographic methods. We used a C18 reversed-phase column with tetrabutylammonium chloride as an ion-pairing agent with an acetonitrile gradient and a TSKgel G2500PWxl column with water as the solvent for gel permeation chromatography. The separated materials, ranging in size from the monomer to the tetramer, have been characterized by functional-group chemical analysis, while the identification of the piperazine-2,5-dione was done using a pure standard. A greater number of peaks which were also better defined were obtained using the ion-pair reversed-phase method, and open and closed beta-lactam ring polymer forms could be distinguished. Using the gel permeation method, only a few monomer, piperazine-2,5-dione, dimer, trimer and combined amoxicillin trimer and tetramer peaks were obtained with water, although those obtained were quite well defined. The data on the time-course of formation of the oligomers and the amoxicillin degradation product were virtually identical by both methods.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; On-column fluorimetric detection ; Gradient elution ; Dansyl amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fluorimetric detection in the presence of a stationary phase has been applied to gradient elution of dansyl amino acids in liquid chromatography. A 1.5 mm ID quartz tube packed with the same materials as the separation column was employed for the flow cell. Conventional-size columns were employed. The peak height of analytes increased with increasing retention owing to focusing and environmental effects of the stationary phase, leading to improvements in sensitivity, which was pronounced for analytes eluting late. The lower the gradient, the larger the improvement in sensitivity achieved. Detection limits were improved by a factor of up to 5.1 by fluorimetric detection using the packed flow cell, compared with those achieved using a common empty flow cell.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; LC-MS ; Cinchona alkaloids ; New column packing materials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A major problem in the HPLC analysis of alkaloids is the poor peak shape and consequently low resolution, due to the interactions of the basic alkaloids with the residual acidic silanol groups of most reversed phase materials. The performance of new packing materials specially designed for the separation of basic compounds has been studied using mobile phases without the special additives commonly applied in the analysis of alkaloids. Strongly basic Cinchona alkaloids were used as test compounds. Retention characteristics and selectivities of each material were studied, after mobile phase optimisation for the column. The influence of the major factors (nature and content of the organic modifier, pH value, salt concentration) affecting resolution was studied. The mobile phases were chosen so that they could be used in thermospray LC-MS. The addition of salts to the mobile phase improves separation but in general the modification of the mobile phase gave little change in selectivity. The performance of silicabased C18 material proved superior to the polymer materials tested.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Springer
    Aquaculture international 4 (1996), S. 237-252 
    ISSN: 1573-143X
    Keywords: Calcification ; Environmental disturbances ; Eumelanin ; Great scallop (Pecten maximus) ; Shell colour ; microstructure and melanization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Modifications of great scallop (Pecten moximus) shells have been noticed in many sites of scallop fisheries in Brittany, especially in shallow waters. These calcification abnormalities are linked to the appearance of a brown colouration of the internal calcified shell layer, due to the presence of a eumelanin associated with the insoluble organic matrix of the biocrystals. The appearance of this pigment generates many disturbances of the calcified foliated microstructure of the scallop internal shell layer. The mantle structure is not modified in brown shells as compared with white ones. No pathogenic signs such as hyperplasia or haemocytic infiltration have been observed. According to this observation, we hypothesize that the brown colour phenomenon is more a result of environmental disturbance rather than a symptom of a pathogenic disease. The colour abnormalities of the internal shell layer can be detected by a spectral analysis of its reflectance before it can be detected with the naked eye. This method, correlated to microstructural observations, gives a rapid and precise analysis of the appearance of the pigmentation on adult or juvenile scallops. It may be a useful method for the evaluation of the influence of environmental parameters, for example, on calcification and its abnormalities.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Diode-array detection ; Retinol acetate ; Pharmaceutical preparations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A very simple high-performance liquid chromatographic method for determination of Vitamin A in pharmaceutical preparations without the need for saponification was developed. A reversed-phase (Nova-Pack C18, 4 μm) column was used with a mobile phase of acetonitrile-tetrahydrofuran-water (55∶37∶8) and a flowrate of 1.5 ml/min. Sample treatment only consisted of the extraction of retinol acetate content from capsules or tablets with methanol. Total extraction was achieved by shaking vigorously with the aid of magnetic stirring for three hours at room temperature. No change of solvent is necessary to introduce the sample in the chromatographic system. This method is suitable for routine quantification of Vitamin A.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 193-196 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemometric methodology ; Elution order ; Simplex optimization ; Benzodiazepines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Using a rapid chemometric methodology to determine the separation factor, α, at different temperatures, Gibbs Helmholtz parameters (Δ (ΔH), Δ (ΔS), Δ (ΔG)) of two adjacent benodiazepines on a chromatogram were obtained from ln α versus T−1 plots. A temperature dependent reversal of the elution order was studied and the mobile phase composition and column temperature were optimized to obtain the best separation. A flow rate of 0.80 ml min−1 with 52.6% methanol in the methanol-water mixture and a column temperature of 48°C gave the most efficient separation of ten benzodiazepines.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 237-246 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mixed mode stationary phases ; Indirect photometric and fluorometric detection ; Conductimetric detection ; Alkyl-sulphates, and sulphonat-phosphates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Separation of three classes of anionic surfactants (alkyl sulfates, alkanesulfonates, and alkyl phosphates) are achieved on a mixed-mode reversed phase (RP) phenyl/-anion exchange column using a naphthalenetrisulfonate (NTS)-acetonitrile (ACN) mobile phase via indirect photometric, indirect fluorometric, direct or indirect conductivity detection. Mixtures of C5−C18 sulfates, C6−C18 sulfonates, and C1−C4 phosphates (mono- and di-ester) can be separated in less than 20, 24, and 20 min respectively. Although hydrophobic effects are more pronounced in mixed-mode chromatography, equivalent-per-equivalent exchange of analysis and eluent ion is still required for sensitive indirect photometric, fluorometric, or conductivity detection. The detection limits of alkyl sulfates and alkanesulfonates are in the range of 3–15 pmoles which are at least an order of magnitude better than suppressed conductivity detection. The determination of surfactants in a variety of real samples is also presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 287-295 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary zone electrophoresis ; Enantioseparation ; Carnitine ; Derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Carnitine is an essential component in tissues of animals, higher plants and many microorganisms. Whereas the L-carnitine enantiomer plays an important role in the metabolism of long chain fatty acids, D-carnitine has a considerable toxic influence on biochemical processes. The analytical separation of D-and L-carnitine depends upon derivatization with UV-or fluorescently active substances, e.g. FMOC and (+)/(−)-FLEC. The separation of diastereomeric (+)- and (−)-FLEC carnitine esters was performed successfully with capillary zone electrophoresis (CZE) and HPLC, after optimization of the derivatization process and of the composition and pH of the buffer, using UV- and fluorescence detection. With HPLC separation a detection limit of the carnitine esters of 5 μmol/l when using fluorescence detection was achieved. With both separation systems baseline resolution and short analysis times could be obtained. The enantiomeric FMOC derivatives could be separated using the electrophoretic system and acidic buffers with high concentrations of an osmotic flow modifier together with γ-cyclodextrine as chiral selector. The applicability of the optimized separation conditions are demonstrated in the analysis of agar culture medium inoculated withPseudomonas putida and of pharmaceutical formulations. In all samples very low amounts of D- or L-carnitine could be determined in the presence of the other enantiomeric form. Problems caused by the impurity of the carnitine standards or the derivatization agent (+)/(−)-FLEC are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fullerenes ; Retention vs NMR spectra ; C18 phases ; Low temperature separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The temperature effect on the retention of fullerenes in the range 80°C to −70°C in liquid chromatography (LC) has been examined using octadecylsilica stationary phases (ODS). It has been found that the maximum retention temperature lies around −10°C with a highly carbon loaded ODS phase. Solid state CPMAS NMR measurements on the stationary phases indicated that the relaxation time at the 30 ppm methylene signal changes with the temperature and has a minimum relaxation time at the temperature which closely matches the maximum retention temperature observed in chromatography. The interpretation of both NMR spectroscopic and LC chromatographic data are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 40 (1995), S. 601-606 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amino acid analysis ; Chirality ; Diastereoisomers ; Dipeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Using a robotic autosampler, free DL-amino acids were derivatized with highly reactive, urethane-protected, L-α-amino acidN-carboxyanhydrides (NACs) with structures: Boc-Phe-NCA, Boc-Asn(Trt)-NCA, Fmoc-Lys(Boc)-NCA, Fmoc-Met-NCA, Fmoc-Ala-NCA, Z-Ala-NCA, Z-Val-NCA and Z-Leu-NCA (Boc=tert-butyloxycarbonyl, Trt=trityl, Fmoc=9-(fluor-enylmethyl)oxycarbonyl, Z=benzyloxycarbonyl). Using sodium borate buffer and acetonitrile solvent, derivatization was complete in 3.5 min at room temperature. By selection of an appropriate reagent, the resulting diastereomeric,N-protected dipeptides were separated on an octylsilica stationary phase using mixtures of sodium acetate buffer and acetonitrile as eluents.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dihydroxyacetone ; 2,4-dinitrophenylhydrazine ; Tanning creams
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and simple HPLC method for the identification and determination of dihydroxyacetone, a tanning agent widely used in a variety of preparations, is presented. The method consists of the analysis of the formulated products after a derivatization reaction which enhances the response and the detection limit of the chromatographic analysis. The characterization and the elucidation of the spacial geometry of the synthesized derivative are described.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 41 (1995), S. 431-434 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Patent Blue V in cheese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The HPLC method developed for the analysis of the dye Patent Blue V in extracts from cheese is sufficiently sensitive to detect and measure concentrations above 0.1 ppm with a standard deviation of 3%. The extraction procedure described gives a recovery from cheese of about 80%. The method has been applied to commercial samples of cheese and a concentration of the dye of about 0.12 ppm was measured in one case.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid chromatography ; Neural networks ; Retention modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Multi-layer feed-forward neural networks trained with an error back-propagation algorithm have been used to model retention behaviour of liquid chromatography as a function of the composition of the mobile phases. Conventional hydro-organic and micellar mobile phases were considered. Accurate retention modelling and prediction have been achieved using mobile phases defined by two, three and four parameters. With micellar mobile phases, the parameters involved included the concentrations of surfactant and organic modifier, pH and temperature. It is shown that neural networks provide a competitive tool to model varied inherent nonlinear relationships of retention behaviour with respect to the mobile phase parameters. The soft models defined by the weights of the networks are capable of accommodating all types of linear and nonlinear relationships, neural networks being specially useful when the relationships between retention behaviour and the mobile phase parameters are unknown. However, to train neural networks more experimental points than with hard-modelling methods are required, hence the use of the networks is recommended only for those cases where adequate theoretical or empirical models do not exist.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Diltiazem hydrochloride stereoisomers ; Chiralcel OF ; Chiral inversion ; Epimerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The simultaneous stereospecific assay of four stereoisomers of diltiazem hydrochloride in bulk drug and aqueous solution was developed using HPLC on a Chiralcel OF column. The four isomers were quantitated with good precision by the internal standard method. The chiral inversion of (+)-cis-diltiazem hydrochloride in vitro, stability of its (2S, 3S) configuration in the solid and aqueous states was examined by HPLC. Chiral inversion of (+)-cis-diltiazem hydrochloride was not observed in the solid state, and its (2S, 3S) configuration was stable to heat, humidity and light. Chiral inversion of (+)-cis-diltiazem hydrochloride (2S, 3S) was observed in aqueous solution under UV, but not in aqueous solution stored at 80°C for 5h nor under visible light for 10 h. The (+)-cis-diltiazem hydrochloride (2S, 3S) epimerized to (+)-trans-diltiazem hydrochloride (2R, 3S) with a half-life of 5h in aqueous solution under UV but the reverse chiral inversion of (+)-trans-diltiazem hydrochloride (2R, 3S) to (+)-cis-diltiazem hydrochloride (2S, 3S) was not observed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 41 (1995), S. 488-491 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Acetonitrile disposal ; Acetonitrile hydrolysis ; Degradation kinetics ; Waste solvent management
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Acetonitrile is one of the most frequently used solvents in column liquid chromatography. Because of its toxicity, safe disposal of the waste solvent is essential. Combustion in a hazardous waste plant, if available, is recommended. Otherwise the waste can be degraded in the laboratory to acetic acid and ammonia by treatment with sodium hydroxide. The addition of hydrogen peroxide is not necessary. The waste needs to be diluted to 10% acetonitrile in water in order to prevent the formation of a two-phase system on addition of concentrated sodium hydroxide. This reagent must be added in excess; 2.5 mols of sodium hydroxide per mol of acetonitrile are recommended. It was found that the kinetics are of second order, with an activation energy of 89 kJ mol−1 and a frequency factor of 9×109. Therefore even at room temperature degradation is possible, although a hydrolysis time of approximately 15 days is needed under these conditions. At 80°C, where refluxing is not necessary, hydrolysis is complete after, e.g., 2 h, depending on the amount of sodium hydroxide added.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair LC ; 5-Sulphoquinoline-8-ol ; Metal complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reversed-phase ion-pair liquid chromatographic behaviour of several metal complexes with 5-sulphoquinoline-8-ol (HQS) on an octadecyl-modified silica column was investigated by using a fluorescence detector. The aluminum complex gave two peaks on the chromatograms when eluents containing phosphate buffer were used. The effects of the pH of the eluent, HQS concentration, the nature of anions in the eluent, and the column temperature on the retention behaviour of the aluminum complex are discussed on the basis of the equilibria and the kinetics of the complexation of the aluminum ion with HQS and anions in the eluent. The equilibrium constant for the interconversion reaction between the two Al(III)-HQS species which correspond to the two peaks observed and the second stepwise formation constant for the Zn(II)-HQS complex were evaluated from the HPLC data obtained.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fluorescamine derivatives ; Aniline and aniline derivatives ; Environmental waters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fluorescamine (fluram) has been used as a fluorogenic compound for pre-column derivatization of aniline and some derivatives. Anilines were derivatized with fluram in citrate buffer media (pH 5.5) to form pyrrolinones. The highly fluorescence pyrrolinones were isolated and pre-concentrated by solid phase extraction. A reversed phase, Spherisorb RP-8 column and tetrahydrofuran: water:formic acid (42∶56∶2) mobile phase was used for separation. Detection method was by a sensitive fluorimetric method and quantitation was at 395 and 495 nm. The various parameters such as reaction conditions between anilines and fluram, solid phase extraction and chromatographic separation were optimized. Calibrations were linear over the range considered with excellent correlation coefficients (r〉0.999). Relative standard deviations are less than 2.5% and detection limits for aniline,p-toluidine, 4-chloroaniline and 4-bromoaniline were 6, 30, 6 and 8 ng L−1, respectively. This method has been used successfully for the determination of anilines in environmental waters.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nauclea diderrichii (de Wild) Merr ; Saponins ; Alkaloid glycoside ; Chrysanthelline A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase HPLC determination of 11 saponins and an alkaloid glycoside inNauclea diderrichii bark is described. Quantitative analysis of quinovic acid 3-O-α-L-rhamnopyranoside which is one of the main saponins was determined, using Chrysanthelline A as internal standard. The complete separation was achieved in 47 minutes. The method of quantification was validated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Polychlorinated biphenyls ; Cod liver oil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By application of a chromatographic column filled with Supelclean ENVI-Carb/Celite and elution with three solvents of different polarity three PCB fractions were obtained. Fraction A contained poly-ortho PCBs, Fraction B mono-ortho PCBs, and Fraction C non-ortho PCBs. The Supelclean ENVI-Carb/Celite column was used in combination with a sample preparation procedure for pre-cleaning of acid-stable chlorinated hydrocarbons such as DDT and its metabolites, HCH isomers, and regulation-relevant PCB congeners. The method was optimized using standard solutions of 55 PCB congeners, 8 chlorinated pesticides and contaminated cod liver oil samples. The influence of traces of remaining matrix on the elution profile of the organochlorine compounds on Supelclean ENVI-Carb/Celite was observed. Quantitation was carried out by GC-ECD with fused silica capillary columns of different polarity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Heterocyclic aromatic amines (HAA) ; Electrospray MS-MS detection ; Selected reaction monitoring (SRM)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Sensitive and selective detection of the sixteen most abundant heterocyclic aromatic amines (HAA) has been achieved by application of high performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS-MS) in combination with selected reaction monitoring (SRM). Detection limits between 0.1 and 50 ng mL−1 were established by use of HAA model solutions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column switching ; Step-gradient elution ; Optimization ; Trace analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A computer spreadsheet application has been developed for the optimization of step-gradient elution conditions as applied in coupled-column RPLC for online clean-up and separation in the analysis of pesticide residues. The procedure is based on the experimentally determined retention behaviour of the analytes as a function of mobile phase composition. Retention and peak volumes of the analytes eluting under isocratic and one- and/or two-step gradient conditions can be calculated. For a given set of analytes, the spreadsheet systematically calculates the resolution of the least efficiently separated pair of peaks in the space defined by the eluotropic strengths of the mobile phases and the time at which the step-gradient takes place. The performance of the proposed procedure was tested and evaluated for the analysis of nine polar pesticides for which in a previous study adequate conditions had been found by computer-aided chromatogram simulation. the optimum conditions predicted by the procedure were in good agreement with those established experimentally and by simulation. The simultaneous production of data on retention, peak volume and resolution for a group of analytes under selected one- and/or two step-gradient elution conditions makes the calculation procedure highly productive and flexible in searching for and/or adjusting appropriate separation conditions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydrous zirconium oxide ; Porous polymer resin ; Disubstituted phenols ; ortho-Benzoic acid derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A porous polymer resin loaded with hydrous zirconium oxide (Zr-gel) was evaluated as a stationary phase for the liquid chromatographic separation of disubstituted aromatic compounds. The prepared Zr-gel was used to separate disubstituted phenols andortho-substituted benzoic acid derivatives in reversed-phase mode. The retention time of catechol was greater than those of other disubstituted phenols; this implies that the Zr-gel has specificity for the phenolic hydroxyl group. The retention behavior ofortho-substituted benzoic acid derivatives on the Zr-gel was also evaluated in reversedphase mode using buffer. Phthalic acid was specifically retained in the vicinity of pH 6.0, which has been regarded as the equal adsorbic point. Similar behavior was also observed for salicylic acid, although the retention time of salicylic acid was less than that of phthalic acid. It seems that the specific retention behavior of hydrous zirconium oxide is a result of complexation with ligands such as hydroxyl and carboxyl groups. The results of this study have revealed that the retention mechanism of hydrous zirconium oxide is a combination of ion exchange and interaction based on complexation with ligands.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Tryptophan ; Chiral separations ; Diode-laser polarimetric detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The combined utilization of photometric, fluorimetric and polarimetric detection liquid chromatography detectors in series for the identification and quantification of D-tryptophan and L-tryptophan was evaluated. Detection limits of about 1 μg were established with the range of linearity extending to about 100 μg. The relative standard deviation of the D-form and L-form tryptophan were 7.32 and 4.22%, respectively. The amount unknown of tryptophan enantiomers in the different mixtures was determined with an accuracy of 1.58% at the 40 μg injection level.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Un-sulphated and sulphated surfactants ; Oligoethyleneglycol nonylphenyl ethers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention behaviour of un-sulphated and sulphated, oligoethyleneglycol nonylphenyl ether, anionic surfactants was investigated in normal-phase LC systems with chemically bonded amino stationary phase in organic mobile phases containing water and cetyl trimethylammonium bromide (CTAB). Addition of water to the mobile phase improves efficiency of separation and linearity of the dependences of logk′ versus number of oxyethylene units in the sulphated oligomers, so that it is possible to describe simultaneous effects of this number and of the concentration of CTAB on retention by a simple equation. In this system, it is possible to separate lower sulphated and un-sulphated oligomers in a single run in 10–15 min under isocratic conditions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrothermal atomic absorption spectrometry ; Vitamin B12 analogues ; Cobalamins and cobalt ; Meat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The coupling of liquid chromatography and electrothermal atomic absorption spectrometry (LC-ETAAS) lowers the detection limit for identification of vitamin B12 analogues. Cobalamins and aqueous cobalt (II) were separated by reversed-phase liquid chromatography using a linear gradient: 26∶74 (v/v) methanol:0.05 M phosphate buffer (pH 4.2) to 50∶50 mixture over 8 min. The vitamins were quantitatively determined in the column effluent by measuring total cobalt by ETAAS. The analysis of meat and liver extracts by LC-ETAAS showed that the matrix did not interfere with the determination of cobalt. Hence, recoveries of cobalt in spiked meat and liver samples were satisfactory.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 42 (1996), S. 405-408 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Meropenem in rat plasma ; Column-switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The purpose of this study was to develop a columnswitching HPLC method for the determination of meropenem in plasma. This method showed excellent precision and accuracy with good sensitivity and speed. The total analysis time per sample was less than 20 min and the mean coefficients of variation for intra- and inter-assay were less than 4.0%. The method has been successfully applied to plasma samples from rats receiving an intraperitoneal injection of meropenem.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiol drugs ; Pre-chromatographic derivatization ; 1,1′-[ethenylidenebis(sulfonyl)]bis-benzene reagent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of 1,1′-[ethenylidenebis(sulfonyl)]bis-benzene as a pre-chromatographic reagent for LC analysis of thiol drugs is proposed. The reagent reacts rapidly (2 min) under mild conditions (pH 7.5, ambient) with thiol drugs and the resulting adducts can be chromatographed under reversed-phase conditions (C-18 column). Excess reagent can be removed from the reaction mixture by simple liquid-liquid extraction with chloroform. The HPLC method using UV detection was successfully applied to the analysis of reduced glutathione (GSH), N-acetylcysteine, N-2-mercaptopropionylglycine and captopril in their commercial formulations.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; 2-Arylpropionic acids ; Barbituric acids ; Benzodiazepines ; Cellulose tris(4-methylbenzoate) chiral stationary phase ; Reversed-phase mode ; Chiral recognition mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A newly developed reversed-phase chiral stationary phase, cellulose tris(4-methylbenzoate), known as Chiralcel OJ-R, has been successfully applied to the direct resolution of the enantiomers of several nonsteroidal anti-inflammatory drugs belonging to the profen group. Among the five barbituric acids tested, the chiral resolution of mephobarbital is especially high. The Chiralcel OJ-R column also proved quite efficient for the enantiomeric resolution of a few representatives of the benzodiazepine group. Variations of mobile phase conditions based on acetonitrile and/or methanol were tested. The results obtained are briefly compared with separations performed using a Chiralcel OJ column under normalphase conditions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    ISSN: 1612-1112
    Keywords: Liquid-liquid and liquid-solid extractions ; Column liquid chromatography ; Mass spectrometry detection ; Flavonoids inPhillyrea angustifolia leaves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Liquid-liquid (LLE) and liquid-solid extraction (LSE) procedures were developed to identify polyphenols in phillyrea (Phillyrea angustifolia L.) leaves. The liquidsolid extraction, carried out by using two serial Bond-Elut® CH and Bond-Elut® SAX cartridges allowed the collection of both polyphenols and soluble carbohydrates during a single extraction of leaf. This method seems to be suitable for both phytochemical and physiological study of the species, allowing the identification of two classes of organic compounds which have a central role in the metabolism of phillyrea plants. A method of isolation and concentration of polyphenols for further molecular characterization, using centrifuge chromatography, was also developed. Molecular characterization, carried out by UV-Vis spectrophotometry and mass spectrometry, demonstrated the presence of compounds with interesting biological activity, i.e. flavonoids and oleuropein derivatives. The soluble carbohydrate composition of phillyrea leaves did not substantially differ from that ofOlea europaea L. leaves, except for a higher mannitol/glucose ratio. This carbohydrate distribution may be linked to the evolution pattern of this species which usually grows in severely stressed environments.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; On-line liquid chromatography-mass spectrometry ; Neutral and acidic cannabinoids ; Hashish samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper reports the use of liquid chromatography for the separation and determination of the major cannabinoids extracted from hashish samples. The direct coupling to the mass spectrometer enables the selective identification both of neutral and acidic cannabinoids. The developed method does not require any preliminary derivatization and should, therefore, be of interest in forensic analysis for simple and unequivocal determination of hashish constituents.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Non-linear adsorption isotherm ; Simulation of chromatographic peak profiles ; Separation of optical isomers ; Non-racemic mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This article discusses the effect of solute association on the apparent adsorption isotherm and on the chromatographic peak profile. The modelling performed has shown that dimerization of a solute in a chromatographic system gives rise to an apparent adsorption isotherm of the non-linear type. This results first of all in peak broadening. Tailing or a fronting can be observed depending on the relative retention of the monomer and the dimer. Secondly, the retention of the solute depends on the amount of sample because of the non-linear character of the adsorption isotherm. As a result, an excess of one of two analytes with absolutely identical adsorption properties i.e. optical isomers, can be separated in such chromatographic systems by considering that the sample contains non-equal amounts of two analytes. The phenomenon is illustrated by simulated chromatograms of the separation of non-racemic mixtures of enantiomers.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydrous zirconium oxide ; Porous polymer resin ; Silica gel ; ortho-Benzoic acid derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Silica gel loaded with hydrous zirconium oxide (Zr-gel-S) has been prepared and the influence of the base material on the retention behavior ofo-phthalic acid on the hydrous zirconium oxide was evaluated. The retention behavior of the acid on the Zr-gel-S was compared with that on Zr-gel-5, the polymer-based Zr-gel. Comparable retention behavior,i.e. maximum retention in the vicinity of pH 6, which has been regarded as the equal adsorbic point, was observed for both types of Zr-gel, although there was a large difference in the retention times. The difference in retention on the two types of Zr-gel could be ascribed to nature of the base material. The results in this experiments showed, however, that the specific behavior at pH 6 was an essential characteristic of hydrous zirconium oxide and was not related to the influence of the base materials.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sterols, tocopherols, retinols and carotenes ; Dairy products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We have previously described a normal-phase HPLC method for the simultaneous determination of α, β, γ and δ tocopherol, thecis andtrans isomers of retinol, and total carotenes in different Italian cheeses and milk. In this paper we describe a reversed-phase HPLC method using solely methanol as the mobile phase for the determination of α-tocopherol, β-+γ-tocopherols, total retinols, cholesterol, β-sitosterol, campesterol and stigmasterol, and α- and β-carotene. The method developed has been applied to some new dairy products such as natural Quark, with olive, basil or banana and to processed cheese with tomato and the results have been compared with the corresponding results obtained by the normal-phase method. The conclusion is that more complete evaluation of the tocopherol, retinol, carotene and sterol content of dairy products, especially when vegetables and fruits are present, is necessary and can be obtained using both the normal- and reversed-phase HPLC methodologies.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Diode-array detection ; Particle beam mass spectrometric detection ; Pesticides in water ; On-line solid-phase extraction (SPE)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A group of pesticides has been determined by liquid chromatography with diode-array detection (DAD). The coupling of a particle-beam (PB) mass spectrometer to the outlet of the DAD enabled the identities of the pesticides to be confirmed from mass spectra obtained by electron impact ionization. On-line trace enrichment of 200 mL of sample with a PLRP-S precolumn enabled most pesticides to be determined in real samples at levels between 0.2 and 5 μg L−1 and with limits of detection (LOD) between 0.05 and 0.5 μg L−1. In the analysis of real samples, one of the pesticides studied was determined by DAD and its identity was confirmed by comparison of PB mass spectra. The use of PB-MS also enabled the detection of non-target compounds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary electrophoresis ; Phenolic compounds ; Water samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A comparative study of high-performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE) for determination of eleven EPA priority phenols in water samples is discussed. The repeatability, linearity and detection limits of both methods are compared. A solid-phase extraction method using a highly cross-linked styrene-divinylbenzene copolymer sorbent is used for the off-line preconcentration process in order to determine these compounds in water at low levels. Both methods are used to determine phenolic compounds in Ebro river and industrial waste water. Identification was achieved by comparison of the UV spectra corresponding to the different peaks, acquired with a diode-array detector, with those in a spectral library.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polycyclic aromatic hydrocarbons ; Waste waters ; Sewage sludge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A modified solid-phase extraction technique using sonication of the adsorbent material instead of the elution normally applied has been compared with two conventional liquid-liquid extraction procedures for the determination of the 16 EPA PAHs in municipal waste waters by means of HPLC coupled with fluorescence detection. Liquid-liquid extraction with cyclohexane proved to be the most efficient and simplest procedure. Clean-up of the waste-water extracts was not considered necessary, because of the high chromatographic resolution of the column and the selectivity of the fluorescence detector. Different organic solvents were also compared for ultrasonic extraction of PAHs from sewage sludge. The best results were obtained by use of acetonitrile. Clean-up of sewage-sludge extracts was not found necessary for accurate quantification of the major PAH components with fluorescence detection. The precision of the whole analytical procedure from extraction to the final determination of PAHs was satisfactory for both waste-water and sewage-sludge samples.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 43 (1996), S. 117-123 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-exchange chromatography ; Ion-exchange mechanism ; Optimization of alkali and alkaline earth separation ; Crown ether complexing reagents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The elution behavior of alkali and earth alkaline cations has been studied on a newly synthesized weak cationexchanger (WCX). Applying this stationary phase isocratic separation of these cations is possible. The dependence of retention on competing ion concentration is described via a simple model. The influence of crown ethers as well as organic eluent additives on selectivity and peak efficiency is demonstrated. With optimized separation such cations can be determined with detection limits of about 0.5 ppm using a conductivity detector without ion suppression.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 43 (1996), S. 143-148 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid chromatography ; Ion-exchange-induced stationary phase ; Dansyl amino acids (Dns-AAs) ; Fluorescence enhancement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behavior of dansyl amino acids in micellar liquid chromatography has been examined by using ionexchange-induced stationary phases. Several parameters affected the retention of the analytes, including the type and concentration of micellar agent and modifier ion and the concentration of acetonitrile in the mobile phase. The order of elution of dansyl amino acids obtained with the micellar mobile phase was very different from that observed in conventional reversed-phase liquid chromatography. Fluorescence intensities of some dansyl amino acids were enhanced by the micellar mobile phase.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Experimental design ; Direct chiral resolution ; Omeprazole ; Hydroxy-omeprazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A strategy for the optimisation of direct chiral separation of omeprazole and a metabolite, hydroxi-omeprazole, in reversed phase liquid chromatography is described. A factorial design was used, where mobile phase pH, concentration of a mobile phase modifier, ionic strength and column temperature were tested as the variables and enantioselective retention, column efficiency and asymmetry factor as the responses. The experimental results were evaluated with multivariate analyses, which demonstrated that the column temperature and content of mobile phase acetonitrile were by far the most important variables. The enantiomers of omeprazole and one of its metabolites were baseline resolved within 15 minutes. The optimised chromatographic system was used for a separation of the enantiomers of omeprazole and its main metabolite in a patient plasma sample.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemiluminescence detection ; Tiopronin ; Thiols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In previous pharmacokinetic studies tiopronin, a drug used for effective treatment of cystinuria and rheumatoid arthritis, and its metabolite 2-mercaptopropionic acid were analysed by conventional liquid chromatography with pre- and post-column derivatization and UV detection. Now a novel HPLC-coupled chemiluminescence-flow-injection analysis (CL-FIA) method has been developed for the determination of tiopronin and 2-mercaptopropionic acid in urine. The method is based on chemiluminescence from a Ce(IV) oxidation system sensitized by quinine, as proposed earlier by this group, and flow-injection analysis. The method, which has the advantages of high sensitivity and selectivity, simple sample treatment and prompt production of results, has also been preliminarily adapted for pharmacokinetic study of tiopronin in urine.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; UV and electrochemical detection ; Particle beam-mass spectrometry ; Fat-souble vitamin ; Standard-bore and narrow-bore columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The application of different detection techniques; UV, electrochemical (ED) and particle beam-mass spectrometry (PB-MS) for the high-performance liquid chromatography analysis of fat-soluble vitamins were studied. Separation of all compounds examined was performed using both C8 standard-bore and narrow-bore columns for UV and MS detection, whereas in the case of HPLC-ED, a C8 standard-bore column only was used. Detector responses were studied in terms of linear range, detection limit and precision. The HPLC methods with UV, PB-MS and electrochemical detection were applied to the assay of vitamins A and E in an infantformula, powdered-milk sample. Recovery studies showed good results both for vitamins A and E, within-run precision being 2–4% for LC-UV and LC-ED techniques. In addition, excellent aggrement between the results obtained with the detection systems explored was found.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded silica gel ; Mixed solvents ; Steroids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of 30 estradiol and estrone derivatives has been studied on diol, amino- and cyanopropyl silica gel stationary phases with non-aqueous mobile phases. The slopes of linear relationships between the logarithm of the retention factor and logarithm of the volume fractions of the polar components of the binary eluents have been calculated and are discussed in relation to the characteristics of the solute, eluent and stationary phase. An equation for testing the separation efficiency of stationary phases has been derived.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    ISSN: 1612-1112
    Keywords: Thin layer chromatography ; Column liquid chromatography ; Radioimmunoassay ; Cortisol ; Guinea pig ; Urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to collect urinary samples from unrestrained guinea pigs, animals were kept in their familiar home cages with wood shavings for bedding. Cortisol was removed from shavings by a simple washing step, and an attempt was made to measure its concentrations by high performance thin-layer chromatography (HPTLC), high performance liquid chromatography (HPLC), or thin layer chromatography/radioimmunoassay (TLC-RIA). After intramuscular administration of 25 mg cortisol, cortisol excretion increased from about 20–30 μg/day to 400–500 μg/day (HPTLC: 531 μg/day, HPLC: 493 μg/day; TLC-RIA: 394 μg/day). Similarly, the treatment of the animals with 20 IU ACTH resulted in an augmented cortisol excretion, with mean values of 294 μg/day (HPTLC), 256 μg/day (HPLC) and 143 μg/day (TLC-RIA), respectively. The present study shows, for the first time, that cortisol excretion in unrestrained laboratory animals can be determined. Whilst the cortisol values measured by HPTLC and HPLC agree, the amounts measured by TLC-RIA were significantly lower. These differences are probably due to the presence of substances in urine or shavings which interfere with the radioimmunological determination. Hence, cortisol should be determined either by HPTLC or HPLC. Beside having a desirable specificity, these methods are more suited than TLC/RIA for steroid analysis since they confer the possibility of measuring additional steroids (e.g. precursors and/or metabolites of cortisol) in a single urine extract. This is especially the case for the HPTLC method since substances can be transformed into fluorescent derivatives.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 44 (1997), S. 257-262 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microchromatography ; Raman spectroscopy ; Deuterated solvents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A detector for microchromatography in which Raman spectroscopy is used to identify the eluted species has been developed. The detector is designed to be applicable to a wide range of compounds without requiring the presence of a chromophore. Its use is illustrated in the analysis of nitro compounds on a 250 μm i.d. column. Raman spectra of each of the compounds could be identified as they passed the detector. The advatages of the use of fully deuterated solvents are demonstrated by the analysis of nitrobenzenes in methanol/water mobile phases. The detection limit for nitrobenzene using the Raman line at 1342 cm−1 was 75ng.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dipyridamole injection ; Stability studies ; Degradation products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The development and subsequent validation of an isocratic high-performance liquid chromatographic (HPLC) procedure employing ultraviolet (UV) detection for the determination of degradation products in Dipyridamole Injection is reported. The development of this assay involved the evaluation of several factors including buffer type, ionic strength, pH, organic composition, and column type. The described method is simple, reproducible, accurate, and selective. The precision, relative standard deviation (RSD), amongst five sample preparations for total degradation products was not more than (NMT) 10.2 %, while the individual degradation products were NMT 12.1%. Intermediate precision, as determined from fifteen sample preparations, generated by two Analysts on different HPLC systems over three days, exhibited an RSD for total and individual degradation products of 8.2 % and NMT 27.5 %, respectively. The mean absolute recovery of dipyridamole using the described method is 102.1±1. 9%, (mean±SD, n=12) over the concentration range of 0.03 % to 5.0 % of its label claim of 5 mg mL−1. The limit of detection and limit of quantitation were 0.1 and 0.3 μg mL−1, respectively. The linearity of the peak response was verified with respect to dipyridamole concentration over a range of 0.3 and 50 μg mL−1 (0.03 % to 5.0 % label claim). The Standard and Assay Preparations are stable for up to 48 hours at room temperature. The selectivity was evaluated by subjecting the finished product (Dipyridamole Injection) to thermal, acidic, basic, oxidative and fluorescent radiation stress conditions. No interference in the analysis of degradation products was observed, showing the method is stability-indicating.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 44 (1997), S. 295-302 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Open tubular columns ; Weak cation-exchange stationary phase ; Biogenic amines ; LIF detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation and performance of a weak cation-exchange stationary phase for Open Tubular Liquid Chromatography (OT-LC) was investigated. The stationary phase was prepared in 5.4 μm I.D. fused silica capillaries byin situ photopolymerization of a mixture of silicon acrylate and acrylic acid. The influence of pH, counter ion concentration and organic modifier concentration of the mobile phase on the retention was studied with catecholamines as test solutes using LIF detection. Other biological amines like amino acids, small peptides and nucleic acid derivatives could be separated on this stationary phase as well. The kinetic performance of the stationary phase was studied with several cations and neutral solutes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 44 (1997), S. 427-430 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mebeverine in dosage forms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and rapid, high performance liquid chromatographic (HPLC) procedure for determination of mebeverine in dosage forms (tablet and liquid) is described. Reversed-Phase chromatography was carried out using a mobile phase containing 0.05 M ammonium acetate buffer and acetonitrile, [(45%, v/v) pH 5.2] with UV-detection (263 nm). Replicate regression analyses of three standard plots in the concentration range of 0.5–10 mcg mL−1 obtained on three different days gave a correlation coefficient 〉0.9995 and the coefficient of variation of the slopes 〈2.2%. The assay was precise within day and between days as indicated by ANOVA test. The recoveries from 10 replicate tablets of two commercial mebeverine brands and liquid were in order 99.3, 100.5 and 100.1% of the label amount and their coefficient of variations were 1.41, 0.89 and 0.69%, respectively. The limit of quantitation of mebeverine was 5 ng mL−1.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Indirect separation ; Chiral derivatization ; Stable CDA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new chiral derivatizing agent (CDA) (1S, 2S) N-[(2-isothiocyanato)-cyclohexyl)-pivalinoyl amide ((S,S)-PDITC) is described. The CDA is available from 1,2-diamino cyclohexane (DACH) via a straightforward synthesis in both the (R,R) and (S,S)-configuration and can serve as a highly selective, stable reagent for the indirect resolution of chiral primary and secondary amines, amino acids and thiol compounds. The resulting diastereomeric thioureas and dithiocarbamates can be separated by simple RP-HPLC as demonstrated with a number of pharmaceutically important examples of amines and amino alcohol-type drugs. The latter diastereomers are compared with the well-established GITC derivatized compounds. The separation factors (α) of the diastereomeric thioureas range between 1.03 and 2.08 and were usually higher than those of the GITC derivatives. The chemical stability of the PDITC derivatives is excellent due to the absence of hydrolyzable ester groups— considered an advantage compared to GITC derivatives.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Octadecyl titania ; Hydride surface ; Hydrosilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The silanization/hydrosilation bonding method is tested on both a laboratory synthesized and commercial titania. The laboratory titania made by the sol-gel process shows evidence of residual organic material that is removed by an initial acid hydolysis followed by bonding of the hydride (triethoxysilane) under acidic conditions. DRIFT and solid state CP-MAS NMR studies are used to confirm the formation of the hydride layer on the titania and the success of the hydrosilation process for attaching an organic moiety (1-octadecene) to the surface. Chromatographic testing, primarily on the commercial titania based C-18 phase, indicates good reverse phase properties and few residual OH groups, either Ti−OH or Si−OH, as determined by the symmetrical peak shapes obtained for anilines and alkylphenylamines using mobile phases with no buffers or masking agents in the aqueous component.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 47 (1998), S. 25-34 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid Phase Extraction ; RP-HPLC gradient analysis ; Taxus Cell Cultures ; Taxol and Taxanes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Solid phase extraction (SPE) methods are studied for the sample pretreatment for HPLC analysis ofTaxus cell suspension cultures. Various types of SPE materials were tested for the extraction of both the taxane standards and samples of various origin. Comparison between the different cartridges and the different elution solvents are made in terms of extraction recovery and sample clean-up. Selective elution of the taxanes is achieved by a gradient elution scheme.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 47 (1998), S. 77-80 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Stability constants ; Ionic strength ; Heavy metals ; Tartaric acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ion chromatography and potentiometry were used for the determination of the stability constants Pb, Zn, Co, Ni, Mn tartrate complexes at different ionic strengths. An extrapolation function based on the Debye-Hückel equation was applied to obtain the thermodynamic stability constants.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair LC ; Plasma ; 2,4-Toluendiamine ; 2,6-Toluendiamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An ion-pair HPLC method is presented for the determination in plasma of 2,4- and 2,6-toluendiamine (TDA), known carcinogens. The chromatographic conditions consisted in isocratic elution on a reversed phase C18 column with 5 mM octanesulfonic acid in methanol-water, 45∶55, as mobile phase. UV detection was performed at 235 nm. Samples were analyzed after a simple single step liquid-liquid extraction and the method was validated by measurement of precision (interassay and intraassay), sensitivity, specificity, linearity, and recovery. The detection limit for both TDAs in plasma was 20 ng mL−1. The correlation coefficients based on the intrassay calibration curve were 0.998 and 0.997 for 2,6- and 2,4-TDA, respectively. The intraassay accuracy, expressed in terms of recovery, was found to be up to 89.91% and 97.05% for 2,6- and 2,4-TDA, respectively.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomer separation ; Voriconazole (UK-109,496) ; Effect of organic mobile-phase modifier
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Coupled achiral-chiral high-performance liquid chromatography (HPLC) with an achiral amino-based column coupled with a chiral amylose-based column has been used for qualitative and quantitative determination of the potential chiral and achiral impurities of Voriconazole (UK-109,496), a new antifungal agent with two stereogenic centres. The effect of the organic mobile-phase modifier, ethanol, was studied. The assay response was linearly dependent on concentration over the range 1.2–40.4 μg for Voriconazole and 2.5–104.0 ng for the impurities. The limit of detection was 2.5 ng for each analyte.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Titania packings ; Inorganic anions and cations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The ion-exchange retention behavior of titania synthesized in our laboratory was investigated by ion chromatography of inorganic anions and cations. Dilute acetic acid-sodium acetate and bicine-sodium hydroxide buffers were used as mobile phases with no use of suppresor. We observed that the titania, although poor at separating monovalent anions expcept nitrite ion in this experiment, was both an anion and a cation exchanger, and selectively retained fluoride and carbonate ions. We concluded that because of its specific retention properties there were possibilites of using this amphoteric exchanger for simultaneous analysis of anions and cations, and of using it as a selective packing material for ion chromatography.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous graphitic carbon ; Optimization ; Morphine and metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of a series of morphine-based opiates has been investigated using a porous graphitic carbon packing material at acid and alkaline pH. The effects of mobile phase pH, mobile phase organic percentage, column temperature and ionpairing agents were studied. All six opiates were separated within a close retention window despite large differences in measured lipophilicities of the individual opiates. The retention order was not related to the log P values of the opiates and strong retention of the fully ionised compounds was observed, particularly those with acidic functional groups. The effect of pH on the retention of the compounds indicated that the degree of ionisation of the individual compounds was important in the separation mechanism, suggesting that hydrophobic interactions were present in addition to the polar retentive effects observed above. The strong retention of the ionised glucuronide and sulphate conjugates of morphine is a particularly useful feature of the porous graphitic carbon packing material which has general applicability to the analysis of polar or ionised drug metabolites.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...