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  • 1990-1994  (87)
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  • Springer  (87)
  • American Chemical Society
  • American Geophysical Union
  • American Institute of Physics (AIP)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 30 (1991), S. 138-152 
    ISSN: 1436-6215
    Keywords: Ribonucleosides ; RNAcatabolism ; bovinemilk ; goatmilk ; colostral phase ; lactation period ; minor milkconstituents ; buttersera ; intrinsicindicators ; differentiation ofbutter types ; HPLC ; Ribonucleoside ; RNA-Katabolismus ; Kuhmilch ; Ziegenmilch ; Kolostralphase ; Laktationsperiode ; minore Milchinhaltsstoffe ; Butterseren ; intrinsische Indikatoren ; Differenzierung von Buttersorten ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Ribonucleoside gehören zu den minoren Inhaltsstoffen der Milch und zeigen ein tierartentypisches Ribonucleosidmuster. Neben den unmodifizierten Komponenten Adenosin, Cytidin, Guanosin, Inosin und Uridin wurden modifizierte Verbindungen wie N1-Methyladenosin und N6-Carbamoylthreonyladenosin, die aus dem Transfer RNA-Katabolismus stammen, in Einzel- und Sammelmilchen einer kleinen Herde Deutscher Schwarzbunter nachgewiesen und quantitativ über eine gesamte Laktation bestimmt. Die Verlaufsstudie hat gezeigt, daß die Konzentrationsspiegel dieser minoren Komponenten mit Ausnahme der Kolostralphase über die gesamte Laktationsperiode nur einer geringen Schwankungsbreite unterliegen. Ribonucleosidmuster sind deshalb zur Kennzeichnung von Milchen verschiedener Herkunft und Verarbeitung geeignet. Beispielhaft wurden deshalb Ribonucleoside im Verlaufe des Butterungsprozesses bilanziert und gezeigt, daß diesen minoren Komponenten „finger-print“-Eigenschaften zukommen, die zur Differenzierung der von der Butterverordnung definierten drei Buttersorten geeignet sind.
    Notes: Summary Ribonucleosides are minor milk constituents and show a typical pattern which is assumed to be species-specific. As well as the unmodified components adenosine, cytidine, guanosine, inosine, and uridine, modified compounds such as N1-methyladenosine and N6-carbamoylthreonyladenosine — products of the transfer RNA catabolism — have been identified and quantified in individual and bulk herd (race: German black pied) milk samples throughout a whole lactation period. The results of our longitudinal study have shown that — with the exception of the colostral phase — the levels of these minor constituents vary only slightly throughout lactation. These findings imply that ribonucleosides are useful for characterizing milk of different species and technological treatment. Ribonucleosides were determined and balanced, for example, in the course of the churning process, showing that the pattern of these minor milk constituents is useful as a “fingerprint” that allows differentiation between the three butter types defined in the German Federal Butter Ordinance.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 33 (1994), S. 258-266 
    ISSN: 1436-6215
    Keywords: ESR ; HPLC ; Lebensmittelbestrahlung ; Trockenfrüchte ; Kohlenhydrate ; ESR ; HPLC ; food irradiation ; dried fruits ; sugars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary While in a previous work the ESR spectroscopic detection of irradiated dried fruits was reported, in this paper liquid chromatographic determination of the carbohydrate fraction of these fruits is introduced and connected with the ESR results. After irradiation of dried fruits three different types of ESR spectra are observed. In most cases the dried fruits can be attached to these various types by means of their sugar composition. It was also found that the ESR spectra observed for sucrose-rich fruits are very similar to that of pure sucrose. The structure of the ESR spectra can change with storage. Probably, radical rearrangement reactions in the samples are responsible for these changes.
    Notes: Zusammenfassung Nachdem in einer früheren Arbeit der ESR-spektroskopische Nachweis von strahlenbehandelten Trockenfrüchten besprochen wurde, wird in diesem Bericht die flüssigchromatographische Bestimmung der Kohlenhydratfraktion dieser Früchte vorgestellt und ein Zusammenhang zwischen der Zuckerzusammensetzung und den ESR-Signalstrukturen nachgewiesen. Die bei der Bestrahlung von Trockenfrüchten beobachteten ESR-Spektren lassen sich in 3 Typen unterteilen. Die Zuordnung der Trockenfrüchte zu den einzelnen Typen anhand ihrer Kohlenhydratzusammensetzung gelingt in einer überwiegenden Zahl der untersuchten Proben. Weiterhin wird festgestellt, daß die beobachteten ESR-Signale in ihrem Habitus denen der reinen bestrahlten Mono- und Disaccharide ähnlich sind. Dies trifft besonders für saccharosereiche Früchte und Saccharose zu. Die Struktur der ESR-Spektren strahlenbehandelter Trockenfrüchte kann sich über einen längeren Zeitraum ändern. Für die Veränderung werden radikalische Umwandlungen in der Probenmatrix verantwortlich gemacht.
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  • 3
    ISSN: 1572-8773
    Keywords: HPLC ; pseudobactin ; Pseudomonas fluorescens ; siderophores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Several iron binding metabolites (siderophores) of Pseudomonas fluorescens B10 (JL-3133) have been detected using C18 reverse phase HPLC coupled with photodiode array detection methods. This analysis utilized a volatile mobile phase of 90% 20 mm NH4HCO3/10% MeOH, pH 6.5. It has been shown to be applicable to other P. fluorescens strains for the detection of related metabolites. Direct scale-up of the analytical HPLC conditions allowed for the efficient preparative isolation of pseudobactin, the principle siderophore produced by P. fluorescens B10 (JL-3133).
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  • 4
    ISSN: 1572-8773
    Keywords: 2,3-dihydroxybenzoylserine ; enterobactin ; Escherichia coli ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Reversed-phase HPLC separation of enterobactin and its 2,3-dihydroxybenzoylserine derivatives was used for a comparative analysis of mutants of Escherichia coli, defective in the regulation of enterobactin biosynthesis (fur), enterobactin transport (fepA) and enterobactin esterase (fes). A complete separation of all 2,3-dihydroxybenzoylserine compounds was achieved: the monomer (DHBS), the linear dimer (DHBS)2 and trimer (DHBS)3, the cyclic trimer, enterobactin, as well as 2,3-dihydroxybenzoic acid. The production of all these compounds was followed after ethylacetate extraction from acidified culture fluids. Enterobactin was found to be the predominant product in all mutant strains. The mutant strains behaved differently with regard to the breakdown products. All degradation products, such as DHBS, (DHBS)2 and (DHBS)3, were detected in the overproducing fur mutant where both transport and esterase are still functioning, while only the monomer, DHBS, was detected in the fepA mutant and no degradation was found in the esterase-deficient fes mutant. From the pattern of breakdown products it may be inferred that the esterase acts in two different ways, depending on whether transport is functioning or not. Thus, esterolytic cleavage of ferric enterobactin after entering the cells results in a mixture of all three hydrolysis products, i.e. DHBS, (DHBS)2 and (DHBS)3, while cleavage of iron-free enterobactin subsequent to its biosynthesis yields only the monomer. Thus, the results of quantitative HPLC analysis of enterobactin and its breakdown products show that different enterobactin esterase products arise, depending on whether iron is bound to enterobactin or not.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 9 (1990), S. 335-340 
    ISSN: 1432-0789
    Keywords: Amino acids ; HPLC ; Immobilized protease ; Organic matter fractions ; Peptides ; Soil nitrogen ; Soil enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Organic matter was extracted from three soils, a cultivated Berwick sandy loam, a cultivated Franklin loamy sand, and an uncultivated Cumberland silty loam. Gel-permeation chromatography was used to separate organic matter extracts into high- (HMW) and low-molecular-weight (LMW) fractions. Reversed-phase high performance liquid chromatography was used to separate and collect the LMW peptide fractions. Peptide samples were hydrolyzed with immobilized proteases attached to beaded agarose and carboxymethyl cellulose in column and batch reaction systems. The chromatograms suggested that peptides are bound to common soil components. The amino acids released in the greatest percentages were relatively non-polar. Large percentages of serine, glycine, alanine, threonine, and valine were observed in the LMW soil peptides. Little aspartic acid, asparagine, glutamic acid, glutamine, arginine, and no histidine was detected in the LMW soil peptides. The soil peptides released different amino acid percentages and quantities when hydrolyzed by immobilized proteases attached to different supports. The quanitities of amino acids released by batch hydrolysis differed from those obtained with column hydrolysis. Greater quantities of amino acids were released (by both types of immobilized protease) from the LMW peptide hydrolysates of the two cultivated soils than from the uncultivated soil.
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  • 6
    ISSN: 1432-1351
    Keywords: Photoreception ; Extraretinal Photoreceptor ; Chromophore ; Opsin ; Reptile ; Immunocytochemistry ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Since the beginning of this century evidence has accumulated which demonstrates that non-mammalian vertebrates possess photoreceptors situated deep within the brain. While many attempts have been made to localize these sensory cells, studies have either failed or been inconclusive. In this report we have used several experimental approaches to localize the deep brain photoreceptors of the lizard Anolis carolinensis. Using 3 antibodies that bind vertebrate cone opsins, we have immunolabelled cerebrospinal fluid (CSF)-contacting neurons located at the ventricular border within the nucleus ventromedialis of the septum. Western blot analysis indicates that these antibodies recognized a single 40 kD protein in ocular, anterior brain, and pineal extracts. Immunoblots of rodent brain did not show a similar protein band. We have also identified specific retinoids associated with phototransduction (11-cis and all-trans-3,4-didehydroretinaldehyde) within anterior brain extracts. This combined data provides the most detailed analysis of deep brain photoreceptors in any vertebrate. Consequently, we feel Anolis provides an excellent model to study this unexplored sensory system of the vertebrates.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 31 (1992), S. 147-154 
    ISSN: 1436-6215
    Keywords: Sugars ; carbohydrates ; lacticacid ; oralfluid ; HPLC ; glucose ; sucrose ; Zucker ; Kohlenhydrate ; Milchsäure ; Speichel ; HPLC-Analyse ; Glukose ; Saccharose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Eine empfindliche HPLC-Methode wurde für die qualitative und quantitative Analyse von Kohlehydraten und organischen Säuren in Mundflüssigkeiten (Speichel und Zahnplaque) entwickelt. Für die Trennung dieser Verbindungen wurde eine Aminex HPX-87H (Bio-Rad) Chromatographie-Säule verwendet. Alle Komponenten des HPLC-Systems waren mit Edelstahl-Kapillaren verbunden. Die isokratische Elution beider Verbindungs-Klassen erfolgte mit 0,01 n Schwefelsäure. Alle Verbindungen wurden mit einem RI-(Refraktion-Index-) Detektor gemessen. Die Ergebnisse wurden mit einem PC-gestütztem Auswertesystem automatisch gesammelt und integriert. Die zeitbedingte Abnahme der Konzentration von Kohlehydraten im Munde einerseits und die Produktion von organischen Säuren durch Bakterien der Mundhöhle andererseits können mit dieser empfindlichen HPLC-Methode bis zu einer Genauigkeit von 0,1 µg Substanz per Analyse (80 µl) bestimmt werden.
    Notes: Summary A sensitive high performance liquid chromatography (HPLC) assay was developed for the qualitative and quantitative determination of carbohydrate sweeteners and organic acids in oral fluid. To separate these compounds, an ion-moderated partition resin HPLC column (Aminex HPX-87H) was used. All components of the HPLC system were interconnected using stainless steel capillary tubing. Isocratic elution with 0.01 N sulfuric acid provided the profile of both compound classes. The compounds were detected using a refractive index detector. The method employed computerized data collection and integration (Omega-2 system) with a detection sensitivity of 0.1 µg compound per HPLC assay (80 µl). This method is useful in caries research, because it detects minute amounts of sugars and organic acids in oral fluid during clearance studies of various foods in the mouth.
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  • 8
    ISSN: 1436-5073
    Keywords: nifedipine ; HPLC ; column switching technique ; electrochemical detection ; validation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A highly sensitive reversed-phase HPLC method has been developed for the determination of nifedipine in human plasma with electrochemical detection. A liquid-liquid extraction procedure is used in sample preparation with an average extraction recovery of 75%. Removing the highly lipophilic plasma components using a special column switching technique reduced the duration of the HPLC measurement from 30 to 9 min. The method is applicable for the pharmacokinetic characterization and bioavailability study of a sustained-release (retard) formulation of nifedipine and for human drug monitoring as it is indicated by the validation of the analysis method. The assay gave a linear response over the concentration range 2.5–50 ng/ml. All the validation parameters are within the internationally required limits.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 109 (1992), S. 39-45 
    ISSN: 1436-5073
    Keywords: arsenic speciation ; HPLC ; hydride generation ; ICP-AES ; hyphenated techniques ; As(III) ; As(V) ; MMA ; DMA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper deals with the application of high performance liquid chromatography (HPLC), hydride generation (HG) and inductively coupled plasma atomic emission spectrometry (ICP) to determine four species of arsenic: As(III), As(V), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The coupling conditions of HPLC-HG-ICP are given. Two anionic exchange columns (Nucleosil-5SB and Hamilton PRP X-100) are tested and the separation conditions optimized. Two acids (H2SO4 and HCl at different concentrations) are tested to obtain the hydrides. The proposed method is applied to determine four arsenic species in a synthetic matrix simulating a fish extract.
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  • 10
    ISSN: 1436-5073
    Keywords: speciation ; arsenic ; direct separation ; HPLC ; mercury gas chromatography ; anion exchange ; distillation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Methods are described for the speciation of arsenic and mercury in biological and environmental materials. For arsenic various methods were developed to distinguish between more or less toxic arsenic compounds and non-toxic compounds. For the determination of methylmercury a modification of the Westöö procedure was applied for higher contents as well as anion exchange down to levels below 0.1 μg/kg in solids and below 0.1 ng/1 in liquids.
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