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  • Column liquid chromatography  (1,216)
  • Springer  (1,216)
  • Public Library of Science (PLoS)
  • Nature Publishing Group
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  • 1
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; HPLC ; Amino acids ; Sugars ; Biogenic amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Liquid chromatography has been used for the determination of amino acids, sugars and biogenic amines in food. Some special problems, for example, determination of patuline in apple juice, hyoscyamine and scopolamine in french beans preserves, were also solved by HPLC.
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  • 2
    ISSN: 1612-1112
    Keywords: Samarosporin ; Stilbellin ; Emerimicin ; Peptide Antibiotics (peptaibols) ; Fast atom bombardment MS ; Column liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The structural identity of the polypeptide antibiotics, samarosporin I(II) and stilbellin I(II) with emerimicin IV(III) has been established by thin-layer chromatography, quantitative amino acid analysis by ion-exchange chromatography, gas-liquid chromatography of the N-pentafluoropropionyl amino acid n-propyl esters and N,O-bis-pentafluoropropionyl phenylalaninol with quartz capillaries coated with the chiral stationary phase N-propionyl-L-valine-tert-butylamide, and determination of the relative molecular masses and sequence-specific fragments by field desorption fast atom bombardment mass spectrometry. The separation of closely related sequence analogues of the above polypeptides could be achieved by reversed-phase high-performance liquid chromatography with spherical, fully porous octadecylsilyl bonded phases, and 86% aqueous methanol as eluent. The application of both chromatographic and mass spectrometric methods is demonstrated to be most valuable for the characterization of antibiotics with the unusual constituents α-aminoisobutyric acid, isovaline and phenylalaninol. The methology employed is regarded to be applicable to all polypeptide antibiotics of the peptaibol class.
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  • 3
    ISSN: 1612-1112
    Keywords: Donor-acceptor complexes ; Column liquid chromatography ; Caffeine bonded phase ; 7(n-propyl)theophylline silica ; Petroleum residues and asphalts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of a new caffeine phase for HPLC is described. The capacity ratios (k′) of about ten polyaromatic hydrocarbons have been determined. It has been shown that the aromatics were eluted according the number of rings, only slightly influenced by the substituents. The performance of the stationary phase is demonstrated with separations of petroleum asphalts and residues and aromatic mixtures.
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  • 4
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    Chromatographia 20 (1985), S. 213-218 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nitro-PAHs ; Diesel particulate extract ; Column switching-HPLC ; Pyrene-butyric acid stationary phase ; π-acceptor ligands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the determination of nitrated polynuclear aromatic hydrocarbons (nitro-PAHs), in particular 1-nitropyrene, in diesel particulate extracts. The method employs a multidimensional HPLC (column switching) technique with final on-line peak identification by UV-VIS spectral comparison with standards. To achieve exceptional chromatographic selectivity for nitro-PAHs, a new pyrene butyric acid amide phase has been prepared which is capable of forming donor-acceptor complexes with them. With this technique it is possible to confirm the presence of 1-nitropyrene in the range 3–100 ng/mg on filter-collected diesel soot. Its utility was demonstrated with diesel exhaust extracts spiked with varying levels of 1-nitropyrene and proved to be highly selective.
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  • 5
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    Chromatographia 20 (1985), S. 303-307 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion ; Dynamic equilibrium ; Ion-pairing interaction ; Monomer-dimer separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Molecular interaction between uni-uni valent ions and bovine serum albumin was investigated by size-exclusion chromatography. Elution profiles are first presented for salt and protein solutions as samples with water as the mobile phase; then for water and protein as samples with salt solutions as the mobile phase. The results suggest the existence of a dynamic equilibrium between the salt ions and the protein ions as reactants and the ion-pair (salt-protein) complex as a product.
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  • 6
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    Chromatographia 20 (1985), S. 313-322 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Tetracyclines antibiotics ; Quantitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of high-performance liquid chromatography (HPLC) for the identification and determination of tetracycline antibiotics is reviewed. HPLC chromatograms provide fast identification by retention time, tR, and precise quantitation by measurement of peak height or peak area. For separation of tetracycline compounds, most HPLC methods use reversed-phase C18 or C8 columns and UV detection. The HPLC solvent system should have a pH of about 6 to prevent steric changes in the tetracycline molecule. For accurate quantitation it is necessary to avoid tailing and this is accomplished by adding a zwitter ion to the solvent system. Methanol and acetonitrile are frequently used as organic modifiers in these solvent systems. In a single analysis, HPLC methods can be used to separate as many as nine or ten commercially used tetracycline compounds and to determine four to five tetracyclines in commercial tetracycline preparations or in biological fluids.
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  • 7
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amiloride hydrochloride ; Hydrochlorothiazide ; Quantitative determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure for the simultaneous quantitative determination of amiloride hydrochloride and hydrochlorothiazide by high-performance liquid chromatography is proposed. A reversed-phase LiChrosorb C8 stationary phase is used. The eluent consisted of an acetonitrile/0.1M phosphate buffer pH3 (15∶85) mixture, containing 50mM propylamine hydrochloride. In this system amiloride hydrochloride, a basic drug, eluted with a acceptable asymmetry factor (Asf=2.1). A simple extraction procedure with methanol is used. Relative standard deviations of 0.87% and 1.6% were obtained for amiloride hydrochloride and hydrochlorothiazide respectively. Chlorothiazide, a thiazide diuretic, is a suitable internal standard. Furthermore the method is also specific for other thiazide diuretics, potassium-sparing diuretics and loop diuretics and for the respective hydrolysis productes of both drugs. Analysis time is reduced to a minimum; the chromatographic separation is complete within 6 minutes.
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  • 8
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    Chromatographia 20 (1985), S. 487-494 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion chromatography ; Controlled-porosity glasses ; Boron-enriched glass surface ; Adsorptive properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Controlled-porosity glasses (CPG) are sieves for macromoleculars, very widely applied in chromatographic columns for the separation of polymers and biopolymers by means of size-exclusion chromatography (SEC) and affinity chromatography. This paper deals with the influence of the thermal treatment of CPG on the elution of polymers in SEC columns. The problem is examined for a few mobile phases and for glasses having different porosities. Additionally, the SEC results obtained are compared with the adsorption properties of the glases investigated.
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  • 9
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Ion-exchange ; Barley proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography using either reversed phase or anion-exchange techniques was used for the fractionation of hordein proteins extracted from European barley. A reversed phase method is presented which utilises an Ultrapore column packed with a wide pore (30 nm) C-3 alkylbonded silica support. Using this method up to 20 components may be separated in 54 min. Elution profiles were found to be reproducible. A further method using rapid anion-exchange chromatography indicated that up to 13 components may be separated, a number which is comparable to that found with electrophoresis. The separation of proteins extracted from different barley cultivars indicated that on the basis of elution profiles high-performance liquid chromatography using either reversed phase or anion-exchange offers considerable potential as a method for barley cultivar identification.
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  • 10
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detection ; Cysteinyldopamine ; Tyrosinase ; Autoxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 5-S-Cysteinyldopamine, a new metabolite of dopamine, was determined in urine by high-performance liquid chromatography with electrochemical detection. The catechol was detected in 14 of 21 melanoma patients and 7 of 21 normal subjects; the highest values were 657 μg/day for melanoma patients and 44 μg/day for normal subjects. These results suggest that the cysteine conjugate may arise from autoxidation of dopamine but tyrosinase may also participate in the oxidation.
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  • 11
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    Chromatographia 21 (1986), S. 79-82 
    ISSN: 1612-1112
    Keywords: Thin-layer chromatography ; Column liquid chromatography ; Cellulose conformation ; Hydrophobicity ; DL-amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the purpose of biochemical study, the resolution of non-derivatized DL-amino acids was carried out by using native-cellulose thin-layer and column chromatography. Its resolution capability was known to be in proportion to the increase of environmental hydrophobicity. It is suggested that the resolutions of DL-amino acids might be resulted from the cellulose conformation change under hydrophobic conditions. The model structures of cellulose are proposed in order to understand the mechanism of chiral selection of amino acids on its molecular surface.
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  • 12
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Triacetylcellulose on silica ; Triacetylcellulose, non-dilute ; Enantiomers ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Triacetylcellulose coated on silica is a novel HPLC sorbent introduced for the separation of enantiomers. A comparison of enantioselectivities α, and resolutions R5 of this material with known pure triacetylcellulose I shows considerable differences. From X-ray wideangle diffraction it is suggested that the novel sorbent also consists of the triacetylcellulose modification I, but its degree of crystallinity is probably lower than that of the non-dilute sorbent. The advantages of the two stationary phases are discussed.
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  • 13
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention correlation ; Silica ; Normal and reversed phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The correlation between the retention data of polyaromatic hydrocarbons (PAH) obtained in normal-and reversed-phase liquid chromatography is investigated in order to determine the dominant factors controlling the retention. It is clear that the separation of PAHs on various chemically-bonded packing materials in normal- and/or reversed-phase modes is primarily controlled by the molecular structure and shape. The π-electron interaction between the solute and the stationary phase also contributes to the retention, although pure silica shows a somewhat different behavior.
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  • 14
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    Chromatographia 18 (1984), S. 574-578 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore column ; Flow rate stability ; Performance ; Quantitative analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Some quantitative implications of the use of microbore columns in column liquid chromatography are investigated. Although for several pumps the flow rate stability at 50 μl min−1 is slightly worse than that of pumps operating at 1 ml min−1, the quantitative performance with respect to repeatability and reproducibility of response factors equals that of conventional liquid chromatography. Thermostatting is strongly recommended for microbore column operation.
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  • 15
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    Chromatographia 18 (1984), S. 600-602 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sugars ; Copper (II) complex ; UV detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive method of sugar analysis by HPLC is described in which a copper (II) modified silica gel as stationary phase is used. Detection is based on UV absorption of a complex formed between the sugar, copper, and ammonia.
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  • 16
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    Chromatographia 22 (1986), S. 165-167 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Kepone and its metabolites ; Chlordecone ; Kepone metabolites ; Pesticide analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography (HPLC) was used to separate chlordecone (Kepone), and two of its metabolites, hydrochlordecone and dihydrochlordecone. Elution of the three peaks occured after the solvent concentration reached 100% methanol and was maintained at 100% for approximately five minutes. The method was linear for chlordecone in the concentration range of 10 to 100 μg.
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  • 17
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    Chromatographia 22 (1986), S. 189-190 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Serum carotenoids ; Amino-cyano stationary phases ; Gradient Elution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polarities of the carotenoids in human serum are very different; many nonpolar carotenoid hydrocarbons (e.g. β-carotene, lycopene) and highly polar hydroxycarotenoids (e. g. β-cryptoxanthin, zeaxanthin, lutein) can be found among them. Gradient elution chromatography was used for the separation of β-carotene, lycopene, β-cryptoxanthin, lutein and zeaxanthin in serum samples applying amino and cyano packings (Chromsil-NH2, Chromsil-CN). The effects of different stationary phases on the selectivity were compared. The method is particularly suitable for the direct determination of serum levels of carotenoid in serum extracts.
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  • 18
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    Chromatographia 22 (1986), S. 194-198 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Vinyl alcohol copolymer gel ; Hydrophobic interaction ; π-π interaction ; Ionic interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A polymer-based, reversed-phase column (VA-C18), prepared by grafting octadecyl chain onto vinyl alcohol copolymer gel, was investigated for its chromatographic characteristics. n-Alkanes and n-alkyl alcohols were found to be retained only by hydrophobic interaction between the solutes and the octadecyl chain. In the case of aromatic hydrocarbons, in addition to the hydrophobic interaction, π-π interaction between the solutes and the based material was elucidated to contribute to the retention. For aromatic tertiary amines which are known to strongly interact with the residual silanol group of the silica-based reversed-phase columns to produce broadened and skewed peakes, the VA-C18 column also retained these substrates strongly by the combination of hydrophobic, π-π, and ionic interactions. In this case, however, symmetrical peaks were observed. From these results, it was determined that in the case of VA-C18, the base material was found not to produce undesirable effect although the solutes interact with the base. Further conclusion obtained was that in reversed phase liquid chromatography, chromatographic properties of base matrix is highly responsible for the overall retention.
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  • 19
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    Chromatographia 22 (1986), S. 187-188 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anti-inflammatory drugs ; Extraction from serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high performance liquid chromatographic system has been developed for the resolution of ten anti-inflammatory drugs. Isocratic separation was achieved using a Spherisorb 5μm ODS column with an eluent consisting of water-orthophosphoric acid to pH 3.2: acetonitrile: methanol (52∶35∶13). A comparison was made between chloroform/acetonitrile (3∶2) and hexane/ether (1∶1) as solvents for the extraction of these drugs from serum.
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  • 20
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    Chromatographia 22 (1986), S. 191-193 
    ISSN: 1612-1112
    Keywords: Gas chromatography/mass spectrometry ; Column liquid chromatography ; Phenols ; Suspended particulate matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Samples of suspended particulate matter collected in Duisburg were investigated for phenolic compounds. The loaded filters were extracted with dichloromethane for 10 hours in a soxhlet apparatus. The concentrated extract was resolved in cyclohexane and separated into a non polar and a polar fraction on alumina. The polar fraction was taken up in dichloromethane and steam-distilled. The distillate was extracted with ether. After the evaporation of the ether, the residue was resolved in dichloromethane and allowed to react with benzoyl chloride. After adding toluene the solution was reduced in volume and analyzed in a GC-MS system. For the separation of phenols by means of HPLC the enrichment of the phenols was performed without benzoylization. Six phenols were detected: hydroxibenzene, methylhydroxibenzene, hydroxibiphenyl, hydroxifluorene, benzylhydroxibenzene and dihydroxibiphenyl.
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  • 21
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    Chromatographia 22 (1986), S. 292-298 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Arsenic speciation ; Chloride interference ; Urine-seawater samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The presence of high concentrations of chloride in urine and seawater samples interferes with the separation of arsenic species by ion chromatography; single peaks may be split into two or more discrete peaks, as a result of the large differences in the ionic strengths of the mobile and injection solvents. A simple model is proposed to explain this phenomenon.
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  • 22
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    Chromatographia 22 (1986), S. 341-344 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion chromatography ; Cellulose acetate packing ; Polymer separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The elution characteristics of polymeric solutes or inorganic salts in high-performance liquid chromatography were examined with a cellulose acetate column using water as the mobile phase. Polymeric (PVP, PEG, etc.) and ionic solutes eluted in a shorter time than deuterium oxide. The retention times for polymers decreased continuously as the molecular weight increased. The elution characteristic, of polymers is assumed to be affected mainly by size exclusion effect. The retention times for ionic solutes increased with the concentration of the injected solutions and asymptotically approached some constant values. The retention times were also affected by the valence and/or hydration of the ion. It was suggested tha the exclusion of ionic solutes was caused by electric repulsion and/or hydration of ion. It was recognized that the salts which were excluded more strongly were rejected more effectively by cellulose acetate membrane in reverse osmosis. HgCl2 which is not dissociated in aquous solution was observed to be adsorbed strongly on cellulose acetate.
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  • 23
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenylthiocarbamyl amino acids ; Pre-column derivatization ; Gas-phase protein hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC system has been developed in which 23 phenylthiocarbamyl (PTC) amino acids are distinctly separated. Applying this system, the preceding steps in HPLC amino acid analysis i.e. gas-phase hydrolysis of the protein/peptide sample and the pre-column derivatization, were evaluated and optimized. PTC amino acids in HPLC buffer solution are stable for at least 16 hours if stored at 5°–8°C. The sensitivity of the method is in the low pmol range.
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  • 24
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    Chromatographia 22 (1986), S. 373-378 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Validation ; Calibration ; Peak purity ; Confidence and prediction intervall
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Zusammenfassung Die Validierung einer HPLC-Methode umfaßt eine ganze Reihe von Punkten, von denen hier auf zwei eingegangen wird: Peakreinheit und Kalibrierung. Die Validierung einer Trennung ist für eindimensionale Detektoren (UV, RI, ECD u.a.) praktisch nur aus der Peakform möglich. Drei Wege werden aufgezeigt: die Gesetzmäßigkeit der Halbwertsbreite, der Einsatz der Ableitungs-Chromatographie und die Abhängigkeit des Symmetriefaktors von der relativen Peakhöhe. Bei mehrdimensionalen Detektrren (Photodiodenarry im UV) können spektrale Parameter als Absorptionsverhältnis (ratio), Differenzspektroskopie (peak suppression) oder auch ein direkter Spektrenvergleich zusätzlich ausgewertet werden. Bei der Validierung einer Kalibrierung werden die wichtigsten Möglichkeiten wie Vertrauensbereich der Kalibrierfunktion, Voraussageintervall und Vertrauensbereich des analytischen Ergebnisses mit entsprechenden Gleichungen angegeben. Diskutiert wird auch die erreichbare Präzision bei der Methode des externen Standards.
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  • 25
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    Chromatographia 22 (1986), S. 261-267 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Partition ; Ionic solutes ; Counter-ion effect ; Co-ion effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A general model that does not depend upon a specific mechanism is proposed for describing the retention of ionic solutes in partition chromatography in the presence of electrolytes. The effect of various types of 1∶1 and 1∶2 eluent electrolytes on the retention of inorganic ions on a cross-linked polyacrylamide is successfully explained in terms of the model. Capacity factors of ionic solutes can be estimated semiempirically on the basis of the theoretical equation presented.
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  • 26
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phases ; Off-line prepurification ; Urinary 5-hydroxyindolacetic acid ; Electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Determination of serotonin (5-hydroxytryptamine, 5-HT) and its main metabolite, 5-hydroxyindolacetic acid (5-HIAA), became important in clinical chemistry. Commercially available and newly synthetised bonded-phase materials were evaluated in the off-line clean-up procedure of urine samples prior to the determination of 5-HIAA by high-performance liquid chromatography using electrochemical detection. From the point of reproducibility and recovery the best results were obtained employing our newly synthetised material consisting of silica gel support with wide pore diameter (≥20 nm) and large pore volume (≥2.5 cm3 g−1) with a mean (B.E.T.) surface area of 196m2 g−1. It has been modified by mixed chemically bonded C16−C18 phase. The achieved surface carbon coverage was 14.7% C.
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  • 27
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenylthiocarbamyl amino acids ; Gas-phase hydrolysis ; Comparison of HPLC data with classical amino acid ; analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The composition of 10 known (poly)peptides of widely different nature was determined by a previously optimized HPLC-PTC amino acid analysis; for the gasphase hydrolysis and the derivatization step use was made of a Pico-Tag Workstation. Results are in good agreement with those of the classical Moore and Stein technique. Strong points of the new method are its sensitivity which is in the low pmol range (nmol for the classical procedure), and its ease of use. The complete procedure can be carried out within one working day by applying an accelerated hydrolysis step. Finally, the (gas-phase) hydrolysis time of peptides containing IIe/Val sequences could be reduced to 24 hours when hydrolysis was carried out at a higher temperature.
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  • 28
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    Chromatographia 23 (1987), S. 814-817 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin layer chromatography ; Ammonium tungstophosphate ; Aminoacids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of aminoacids on columns of silica coated with different percentages of ammonium tungstophosphate at several buffer phosphate concentrations is reported. The stationary phase shows a high selectivity towards aminobutyric acids and methyl derivatives of tryptophan due to the distance between the carboxylic group and the −NH 3 + group involved in the cation-exchange process and/or to the steric hindrance by a methyl substituent. A relationship between HPLC and HPTLC data has been verified and applied to the prediction of the separation of six aminoacids.
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  • 29
    ISSN: 1612-1112
    Keywords: Aldehydes and ketones ; 2,4-dinitrophenylhydrazine-coated silica gel ; Gas chromatography ; Column liquid chromatography ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary After a brief review of several methods described in the literature this paper discusses air-sampling on 2,4-dinitrophenylhydrazine-coated silica gel and identification requirements for aldehydes and ketones most commonly found in industrial pollution. Quantitative analysis of formaldehyde and acetaldehyde either by GC or by HPLC techniques is established using a dynamic system producing test atmospheres and compared with the usual colorimetric determinations.
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  • 30
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aldehydes ; Annular denuder ; Environmental analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An improved procedure for the HPLC determination of C1−C3 aldehydes in environmental samples is described. These air pollutants are quantitatively collected on annular denuders coated with 2,4-Dinitrophenylhydrazine and analyzed as hydrazone derivatives by HPLC with UV absorbance and voltammetric detection. Collection efficiencies of aldehydes are reported and compared with other available methods. Practical examples of the application of the method are given.
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  • 31
    ISSN: 1612-1112
    Keywords: Estriol ; Urine ; Menstrual Cycle ; Column liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatography (HPLC) assay for estriol in nonpregnancy urine is described. After Enzymic hydrolysis, the estriol is extracted from urine by the sorbent trap technique utilizing graphitized carbon black (Carbopack B). After some washing steps, estriol is desorbed by a suitable solvent system. After solvent removal, the sample is injected into an HPLC column for estriol quantification. Analytical recovery of estriol was 96.1%. The precision of the method was 2.6 and 4.9% respectively at 145 and 10.6ng/ml of urine. The limit of sensitivity was set at 0.8 ng/ml of urine. The mean contents of estriol in the follicular and luteal phases were respectively 11.3 and 38.8 ng/ml of urine.
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  • 32
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Isohydric solvents ; Butyrophenones ; Direct-silica gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The behaviour of butyrophenones in high performance liquid chromatography on silica gel using isohydric solvent systems has been studied. The influence of column temperature, water content, acidity and polarity of isohydric solvents on the retention, column efficiency and resolution of a series of butyrophenones have been investigated. Through the results obtained more insight has been gained into the theoretical aspects of the adsorption process on silica gel with isohydric solvent systems.
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  • 33
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase separation ; Oligodeoxyribonucleotides ; Isolation of pure material
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    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase chromatographic column suitable for the purification of chemically synthesized large oligodeoxyribonucleotides (oligo-DNA) was prepared. The specifications of this column are; the selected silica (Toyo Soda silica) with large pore size (at least 150 Å) and small particle diameter (5 μm desired) should be grafted only with monochloro alkylating reagent of long alkyl chain (sufficiently C18) so that the carbon content of the resultant packing material is 15–16%. Using this column, we could isolate the targeted large oligo-DNA (up to 50mer) in a large scale (75 μg per one cycle) from the impurities in the reaction mixture formed during the automated synthesis by the phosphite method.
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  • 34
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pre-column derivatization ; Ultraviolet detector sensitivity ; Dihydroartemisinin ; Diacetyldihydrofluorescein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of diacetyldihydrofluorescein (DADF) for derivatization of dihydroartemisinin (dihydroqinghaosu, DHQHS) is proposed. The reaction between DHQHS and this reagent in the presence of 4-dimethylaminopyridine (DMAP) and N,N′-dicyclohexylcarbodiimide (DCC) was complete in 8 hours at room temperature giving about 80 per cent theoretical yield. The derivative showed intense UV absorption, thus providing a sensitivity of 0.1 nanogram by UV detection after column separation. The influences of the ratio of the reagents, reaction temperature, chromatographic conditions and the extent of detection linearity were investigated. The reaction gave consistent results and chromatographic separation was not affected by an excess of the reagent or side products.
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  • 35
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    Chromatographia 23 (1987), S. 292-300 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Separation of sugars ; Review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This contribution to the problems of carbohydrate (sugar) column liquid chromatography, evaluates several currently used systems (reversed phase octadecylated silica gel, amino modified silica gel, cation exchangers on polystyrene and on silica gel basis, polyol derivatised silica gel and anion exchange systems). The elution pattern, analysis time, column efficiency and column life time expectancy are considered to be the important points for this comparison. The application of silica gel-based cation exchanger and of polyol derivatised silica gel is new to this field. The comparison and/or evaluation tries to be critical and to come to a conclusion for the choice of a recommended system.
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  • 36
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    Chromatographia 23 (1987), S. 320-324 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore capillary columns ; Polymer based octadecylsilica bonded phase ; Fat soluble vitamins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Separation behavior of fat soluble vitamins on various chemically bonded materials in non-aqueous reversedphases microcolumn liquid chromatography has been investigated. The best performance was found on a polymer-based octadecyl bonded phase. Optimization of separation for vitamins D2, D3, E and E acetate has been tried using this polymer-based column and it has been found that a binary mobile phase consisting of acetonitrile and methanol gave complete separation of fat soluble vitamins.
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  • 37
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Packings of octadecylated microporous glass ; Dimethadione and trimethadione in serum ; Pancreatic stones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The liquid chromatographic determination of trimethadione (TMO) and its methabolite, dimethadione (DMO) were studied by high-performance liquid chromatography (HPLC) on octadecyl-modified microporous glasses, prepared with toluene solution containing octadecyl-dimethylchlorosilane, using two types of microporous glass with various mean pore diameters and/or specific surface areas. Using acetonitrile-water mixtures as eluents, TMO and DMO in human serum were separated on the glasses studied, but with different degrees of resolution. In this present study, we report the development of a rapid and selective HPLC method for the simultaneous analysis of TMO and DMO in human serum.
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  • 38
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange chromatography ; Xylenol orange ; Separation of nickel and zinc
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    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid chromatographic procedure for separating nickel and zinc has been developed. Xylenol orange, which is one of the sensitive and commercially available color-forming agents, was used as a component of the mobile phase. The two ions could be separated on weak anion-exchange gels within 10 min. The procedure was suitable for the determination of nickel and zinc in relatively pure solutions with fairly high sensitivity. The described liquid chromatographic analysis would be also potentially applicable for any aqueous sample containing trace levels of metal cations at 1–10 ppm.
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  • 39
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    Chromatographia 23 (1987), S. 395-400 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Photokinetic data ; Reaction mechanism ; (E)-1-phenylpropene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A combined method of high-performance liquid chromatography and UV-absorption spectroscopy is described for use in dynamic systems. It provides a way of obtaining detailed mechanistic information as well as quantitative data (rate constants, quantum yields), even though neither mechanism nor photoproducts are known. The kinetic treatment of the photoreaction of (E)-1-phenylpropene was successful, showing a photo-isomerization and a parallel step. Information on this additional step is obtained by using HPLC to observe the changes in the concentrations of the reactants' selectivity. The necessity of process control is demonstrated.
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  • 40
    ISSN: 1612-1112
    Keywords: Hydrolysis, high temperature ; Column liquid chromatography ; Ion-exchange ; Cellulose ; Oligomeric and monomeric sugars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The hydrolysis of different cotton materials under hydrothermal conditions was investigated. For the analysis of the resulting reaction products high-performance liquid chromatography and gel-permeation chromatography were applied. HPLC columns with ion exchange materials as stationary phases (HPX 87P and Shodex S801) enabled the separation of monomeric sugars and degradation products. Oligomeric sugars were analyzed using a gel column (Bio-Gel P-2) as well as a HPLC column (HPX 42A). Through identification of additional reaction products the mass balance of the hydrolysis can be improved and the analysis of the distribution of the oligomeric sugars gives information for the selection of the reaction conditions.
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  • 41
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Non-porous gel ; Alkaline-earth cations ; Arsenazo III
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    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid chromatographic procedure for separating alkaline-earth-metal cations with a non-porous gel column has been developed. Arsenazo III, which is one of the sensitive and commercially available color-forming agents, was used as a component of the mobile phase. Magnesium and calcium could be separated on the nonporous gel column within 55 seconds. The procedure was suitable for the separation of alkaline-earth-metal cations in relatively pure solutions with high sensitivity. Because of its rapidity the described procedure is also potentially applicable for any aqueous sample.
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  • 42
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    Chromatographia 20 (1985), S. 615-617 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Vitamin B2 in food ; Column switching ; Liquid-solid extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Vitamin B2 was enriched by liquid-solid extraction from large volumes of aqueous samples on a short precolumn. The enriched compounds were transferred onto an analytical reversed-phase column and separated by ion-pair chromatography. The equipment used provides the possibility of automation for routine analysis.
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  • 43
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiol drug analysis ; Derivatization by ethacrynic acid ; Pharmaceutical formulations
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    Topics: Chemistry and Pharmacology
    Notes: Summary A high performance liquid chromatographic method has been developed for the determination of aliphatic thiol drugs, such as N-acetyl-L-cysteine, captopril and mercaptopropionylglycine in pharmaceutical formulations. The procedure involves a precolumn derivatization of the thiol drug with ethacrynic acid followed by reversedphase HPLC separation and UV detection. The conditions for a rapid and selective reaction of the thiols with ethacrynic acid have been investigated. The method proved to be suitable for a reliable and selective quality control of commercial dosage forms of the examined thiol drugs.
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  • 44
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    Chromatographia 25 (1988), S. 31-36 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Radioactivity detector ; Solid scintillator ; Fibre-packed flow cells
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    Topics: Chemistry and Pharmacology
    Notes: Summary A new type of flow-cell radiation detector for use in liquid chromatography which is packed with aligned scintillator fibers is described. A primary advantage of the fiber packed cell is that light generated by the scintillator is absorbed to a much less extent by the fibers than by the powder scintillator used in conventional flow cells. A detection efficiency of 55% has been obtained for carbon-14 using 0.1-mm diameter hand-pulled glass fibers. Computer modeling has shown that even better results can be obtained by using smaller and more uniform diameter fibers which will allow better packing. The fiber cell also demonstrates back pressures which are a factor of 50 less than the conventional cell and much less susceptibility to absorption of compounds because of its lower surface area.
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  • 45
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Analgesic peptides ; Opioids ; Glycopeptides ; Glycosylenkephalins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary N 1.5-Glycosyl enkephalins are potent analgesics. Two enkephalin-related glycosyl peptides: [DMet2, Pro5] enkephalin (N 1.5 β-glucopyranosyl] amide and [DMet2, Pro5] enkephalin [N 1.5 β-galactosyl] amide have been prepared following the liquid phase procedure. The chromatographic behavior of both the final glycosyl enkephalins and their synthetic intermediates on reversed-phase columns has been tested. Semipreparative, reversed-phase, HPLC conditions have been developed in order to obtain a simple and rapid procedure for the purification of the two synthetic pentapeptides. Thus, using isocratic elution, injections of 10mg of crude material after gel filtration gave homogeneous (99.9%) glycosyl enkephalins.
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  • 46
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    Chromatographia 25 (1988), S. 919-922 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nifedipine ; Normal phase ; Plasma ; Liquid-liquid extraction
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    Topics: Chemistry and Pharmacology
    Notes: Summary For the determination of nifedipine in plasma a sensitive and selective method is required. The use of ‘on-line’ pre-column enrichment, followed by ‘reversed phase’ separation and UV-detection at 350 nm proved to be too susceptible. Therefore, detection was carried out after a post-column ‘on-line’ reduction and photoreaction step using a fluorescence detector. Although this method proved to be extremely sensitive (limit of detection 0.1 ng/ml plasma) and selective, a number of problems cropped up caused by the reduction agent which finally prevented the procedure being used in routine analysis. As a consequence, the following method was developed. After liquid-liquid extraction of nifedipine a 1/3 of the extract was chromatographed on a normal phase (diOH) system and detected at 235 nm, because detection at 350 nm was not sensitive enough. This method has a limit of detection of 1 ng nifedipine/ml plasma and the calibration curve is linear up to 320 ng/ml. The recovery lies around 82% and the standard deviation for the range 6–320 ng/ml is less than 5%. So far about 2000 plasma samples have been analysed by this method.
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  • 47
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    Chromatographia 25 (1988), S. 957-960 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical Detection ; Ethinyloestradiol
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    Topics: Chemistry and Pharmacology
    Notes: Summary The analysis of ethinyloestradiol in tablets has been carried out by reversed phase high performance liquid chromatography (HPLC) using electrochemical detection. The drug was eluted with aqueous acetonitrile containing sodium acetate as background electrolyte. The mobile phase was used as extracting solvent, and 4-tertpentylphenol was used as internal standard.
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  • 48
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    Chromatographia 25 (1988), S. 969-973 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carboxylic acid phase ; Addition reactions ; Synthesis of new bonded phases
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    Topics: Chemistry and Pharmacology
    Notes: Summary The allyl bonded phase is used as an intermediate in the synthesis of a weak cation exchange material. The double bond is first converted to an aldehyde by an ozonation reaction and then subsequent oxidation to the carboxylate group is accomplished with dichromate. Diffuse reflectance Fourier transform infrared spectroscopy (DRIFT) is used to monitor the conversion process. The presence of the aldehyde functional group is confirmed by reaction with 2,4-dinitrophenylhydrazine. ESCA spectra reveal no residual chromium on the silica surface. The product is tested chromatographically by the retention of alkylarylketones, the ion-exchange behavior of both monovalent and divalent cations, the retention of nucleosides and bases, and the separation of a mixture of hemoglobins.
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  • 49
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; UV detection ; Solubility ; Polystyrene ; Sample precipitation ; Gradient elution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gradient elution of polystyrene standards on reversed phase C18 columns by methanol/tetrahydrofuran or methanol/dichloromethane mixtures yielded a strange effect of the molecular weight of the sample on the specific peak are (mAUs per μg sample injected). The effect did not occur when pure dichloromethane was used as an eluent. Further to this, dependence of specific peak area on flow rate was observed in gradient elution with methanol/tetrahydrofuran mixtures. It was found that these effects were due to polymer elution at the verge of precipitation. Depending on the dwell time of the sample in the column, opalescence occurred that added to the UV signal used for monitoring the elution.
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  • 50
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    Chromatographia 25 (1988), S. 1034-1038 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Determination of propafenone ; 5-OH propafenone ; Reversed-phase
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    Topics: Chemistry and Pharmacology
    Notes: Summary This paper presents a method for the simultaneous detection of propafenone and 5-hydroxypropafenone (5-OH propafenone) using HPLC. The method is sensitive, selective, and reproducible. The chromatographic separation is based on a 25×0.4 cm 5 μm ODS column, a mobil phase of 0.1 M potassium phosphate (K2HPO4) buffer (pH 2.5) and acetonitrile (63∶37), and UV absorbance detection. There is excellent intra- and interassay variation. Retention times of the internal standard, propafenone, and 5-OH propafenone are 4.3, 6.0 and 2.9 minutes respectively. This method shows linearity over the therapeutic range for propafenone and 5-OH propafenone (0.15 to 3.0 μg/ml and 0.075 to 1.5 μg/ml respectively). No interference has been found from other commonly administered drugs, including several antiarrhythmic drugs, at therapeutic levels.
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  • 51
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Soyabean leaf extracts ; Kaempferol glycosides ; Kaempferol
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    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC method is described for the determination of kaempferol glycosides in soybean leaf extracts. The method is rapid and can provide qualitative and relative quantitative results for 9 kaempferol glycosides. The flavonol glycosides are extracted from soybean leaves by shaking the samples in 50% methanol; the extracts are filtered, evaporated to dryness and reconstituted in methanol before further purification through a C-18 Sep-Pak column. The samples are injected onto a C-18 HPLC column, separated by gradient elution with a 1% phosphoric acid: methanol mixture and detected on a UV/VIS diode-array detector. Flavonols were monitored at 265 and 348 nm and spectra from 180 to 400 nm were stored and used as an aid in identification. Relative quantities of the kaempferol glycosides among soybean cultivars were calculated from their proportion of peak area in the chromatograms. Total kaempferol concentration of the extracts was calculated after acid hydrolysis of the kaempferol glycosides to the aglycone and comparison of peak areas to kaempferol standards.
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  • 52
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Weak cation-exchanger ; Styrene-divinylbenzene copolymer
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    Topics: Chemistry and Pharmacology
    Notes: Summary A weak cation-exchanger for high-performance liquid chromatography is obtained by oxidation of either poly(methylstyrene-divinylbenzene) or of poly(chloromethylstyrene-divinylbenzene). Reaction conditions were optimised to yield an exchange capacity of about 4meqg−1 dry resin. The material was evaluated chromatographically as a function of pH, organic modifier, temperature and flow rate. A combination of ionexchange and hydrophobic interaction between the solutes and the packing material was observed. This could be used to provide more options for realising chromatographic separations. Some chromatograms of heterocyclic bases, nucleosides, nucleotides and amino acids are shown.
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  • 53
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    Chromatographia 20 (1985), S. 87-96 
    ISSN: 1612-1112
    Keywords: Time Optimization ; Column liquid chromatography ; Microbore ; Theophylline
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    Topics: Chemistry and Pharmacology
    Notes: Summary Algorithms for the time optimization of an HPLC separation are presented. Resolution, column performance, extra-column variance, capacity factor, and column length are incorporated into these algorithms. Extracolumn variance for a high-speed microbore system (1 mm i. d. column) was assessed using 2nd moment variance and a non-linear extrapolation of tubing length to zero. Extra-column variance, as a function of flowrate, was incorporated into the reduced operating curve of column performance. The use of empirical correction factors for column reproducibility and homogeneity are suggested. Cutting to an optimum length did not degrade column performance. These algorithms were applied to the optimization of a microbore assay for theophylline, in a simple xanthine mixture. Resulting total analysis times were reduced to 10seconds per sample, at a flowrate of 700μl/min.
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  • 54
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Metabolic disorders ; Xanthine and 2,8-dihydroxyadenine ; Urine analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 2,8-Dihydroxyadeninuria and xanthinuria are inborn enzyme disorders which must be under lifelong therapeutic control. Quantitative determination of 2,8-DHA and xanthine using reversed phase HPLC was performed. A new application for the separation of purines shortens analysis-time. Examples of the determination of 2,8-DHA and xanthine before and under certain therapies are shown. Long term monitoring of the patients offers the possibility of a reliable prophylaxis against stone recurrence.
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  • 55
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    Chromatographia 25 (1988), S. 272-278 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyaromatic hydrocarbons ; Molecular parameters ; Retention prediction
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    Topics: Chemistry and Pharmacology
    Notes: Summary The present research studies the possibility of using the correlation dependence between molecular parameters of unsubstituted polyaromatic hydrocarbons (PAH) and their retention in reversed-phase liquid chromatography to optimize the conditions for the separation and identification of unknown peaks on the chromatograms of multicomponent mixtures. A linear correlation equation, that takes the number and environment of the carbon atom in the PAH molecule into account as well as the differences in the specific interactions of isomeric molecules with polar eluent, has been proposed. The adequacy of the proposed PAH retention model was verified by comparing the calculated retention values with the experimental data. The possibility of identifying unsubstituted PAH according to the number of carbon atoms of various types and according to the values of the molecules lengths (calculated on the basis of the retention of these substances under different eluent compositions) was exemplified by various chromatographic systems (reversed phase-eluent-PAH molecules).
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  • 56
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    Chromatographia 25 (1988), S. 327-331 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Olefin group selectivity ; Methylene group selectivity ; Non-aqueous reversed-phase
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    Topics: Chemistry and Pharmacology
    Notes: Summary The effects of mobile phase composition upon olefin group selectivity (the ratio of the retention factor of a n-alkane to 1-olefin of equal carbon number) has been examined for non-aqueous reversed-phase liquid chromatorphy. Under time-normalized conditions, large variations in olefin group selectivities were noted as the mobile phase constitutents were changes. However, methylene group selectivities were found to be insensitive to the nature of the mobile phase under these conditions. Mobile phases containing alcohols demonstrated low olefin group selectivities compared to those containing acetonitrile as weak solvent. The results of this study explain variations previously observed in the LC separation of olive oil triglycerides that differ in the number of methylene groups and double bonds.
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  • 57
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column switching ; Ion-exchange and reverse phases ; Nucleic acid constituents
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    Topics: Chemistry and Pharmacology
    Notes: Summary A method is presented for the separation of purine and pyrimidine nucleotides, nucleosides and bases in one analysis. This method uses both the ion-exchange and the reversed-phase modes for the analysis of these compounds. The modes are coupled through automatic switching valves. The use of these valves permits the isolation of either column during the analysis. The nucleotides are separated on an anion-exchange column and the nucleosides and bases on a C-18 column. Total analysis time is approximately one hour, and a very small volume of a sample can be analyzed. The technique is flexible and mobile phase conditions for one column can be altered without affecting the resolution on the other column. The method is applicable to biological matrices.
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  • 58
    ISSN: 1612-1112
    Keywords: Size-exclusion chromatography ; Column liquid chromatography ; Peptides ; Hydrolysates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gel filtration (size-exclusion) and high-performance liquid chromatography have been used to separate peptic peptides from haemoglobin hydrolysate. Elution profiles on Sephadex G-25 displayed nine fractions with molecular weights lower than 6500 daltons. Each fraction was analysed for total amino acid content and showed less than 1% free amino acids. Reversed phase HPLC, using ammonium acetate buffer and acetonitrile as solvent, was applied to each fraction in order to obtain pure peptide peaks. The importance of acquiring a better knowledge of such an hydrolysate is discussed. Various potential applications of this type of hydrolysate, some of them already being undertaken, are envisaged.
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  • 59
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pheophytinatonicke(II) ; Chlorophyll ; Pheophytin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC determination of pheophytinatonicke(II) (Pheo-Ni) prepared by the replacement of magnesium(II) in chlorophyll with nicke(II) is described. The good separation of PheoNi was obtained by using chemically bonded C18 as the stationary phase and acetone-methanol (50∶50, vol/vol) as the mobile phase. Conventional spectrophotometric method was also used for the determination of PheoNi. For the synthetic samples prepared by mixing (pheophytinato a) nicke(II) [(Pheo-a) Ni] and (pheophytinato b) nicke(II) [(Pheo-b) Ni], analytical values obtained by the spectrophotometric method were very high compared to those obtained by HPLC. In the proposed HPLC method, (Pheo-a) Ni and (Pheo-b). Ni could be determined in the concentration range of 0.028–30μg/ml and 0.038–30μg/ml with relative standard deviations (n=10) of 3.1% and 0.8%, respectively.
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  • 60
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; On-line deproteinization ; Butyl Toyopearl 650-M ; Gentamicin in serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The binding of serum proteins with Butyl Toyopearl (BT) 650-M has been investigated and applied to on-line deproteinization for the HPLC determination of gentamicin components, c1, c1a, c2, in serum. It was found that in 0.4% perchloric acid medium about 36mg of BSA was adsorbed on 1ml of wet gel. Under this condition hydrophilic components such as gentamicin passed through the pre-column packed with BT 650-M, while serum proteins and hydrophobic components were trapped in the pre-column. The ion pair between gentamicin components and pantanesulfonate anion was effectively trapped in a reversed-phase analytical column. It was then eluted and fluorometrically determined by post-column derivatization with o-phthalaldehyde. The recovery was quantitative with good reproducibility at therapeutic concentrations in sera. Several clinical samples were analyzed by the method.
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  • 61
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    Chromatographia 22 (1986), S. 31-39 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gradient elution ; Isocratic elution ; Prediction of optimum isocratic ; Conditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper describes by simple experiments in a pragmatical way by easy rules of thumbs gradient optimization. Besides selection of the stationary phase and initial and final conditions the two other important variables are program time and eluent flow rate. It is demonstrated, that when the product of both, the gradient volume, is kept constant, the solutes are always eluted with the same eluent composition at column outlet. At constant gradient volume, peak broadening depends on flow rate and on the eluent properties (viscosity) at which the solutes elute, and on the time the solutes spend in the column. Because peak broadening increases with increasing gradient volume, the peak capacity in gradient elution shows an optimum at gradient volumes around 15 empty column volumes (program times 45 to 60 min at flow rates of 1 ml/min with standard columns). Gradient elution can also be used for fast evaluation of optimum eluent composition for isocratic analysis. This procedure requires a calibration of the equipment for determination of eluent composition at column outlet. The sample is chromatographed in a standard gradient run of 10 to 15 empty column volumes. The eluent composition at which the solute of interest elutes during the gradient is used for isocratic analysis, where the k' value of this solute will then be around 2.
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  • 62
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    Chromatographia 25 (1988), S. 603-608 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion interaction reagent HPLC ; Separation of amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ion interaction reagent RP-HPLC has been employed for the separation of some typical aliphatic and aromatic amines. The effects on retention of the alkyl chain length of the eluent, and of the eluent flow-rate have been studied. The use of solutions of hexylaminium-, octylaminium-and decylaminium-salicylate has been tested and compared, employing both conductometric and spectrophotometric detection. On the basis of the results obtained, the optimal experimental conditions can be chosen for each separation. Aliphatic and aromatic mono and diamines can be separated and detected, with an average sensitivity of the order of 40 ng without any pretreatment or derivatization. The retention data obtained for amines, compared with those obtained with the same ion interaction reagents for anions, help in the interpretation of the mechanism involved in the technique.
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  • 63
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    Chromatographia 25 (1988), S. 609-612 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Triglyceride composition of grapes ; Identification system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The triglyceride composition of the Tempranillo grape (Vitis vinifera) has been examined by a combination of HPLC and GLC. To identify the triglycerides, equations were applied relating log k′ with the molecular variables: equivalent carbon number, chain length and number of double bonds in each of the fatty acids in the glycerides. Ten triglycerides were found, the principal ones being trilinolein (35.75%), dilinoleyl-olein (21.03%) and dilinoleyl-palmitin (17.02%).
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  • 64
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Racemic resolution ; Effect of temperature
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    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of temperature on the resolution of racemates was investigated with respect to the resolution of racemic mixtures of aminoacid esters and 2,2,2-trifluoro-1-(9 anthryl) ethanol. Generally the capacity factor (k′) was found to increase with decreasing temperature. The values of the difference in the standard change of molar Gibbs energy, (ΔΔG), between the more retained and the less retained enantiomer do not appear to vary in a particular fashion. The sign of the enthalpic (ΔΔH) and the entropic, (ΔΔS) quantities for all the mixtures also depend upon the nature of the solute mixture.
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  • 65
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    Chromatographia 25 (1988), S. 685-690 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Adsorption on solid support ; Polar solutes
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    Topics: Chemistry and Pharmacology
    Notes: Summary The properties of chloroform as a liquid stationary phase in reversed-phase liquid chromatography have been investigated. Stable systems and complete pore filling of the support were obtained. Uncharged acids were slightly adsorbed by the support. Amines in the cationic form showed tailing, which can be attributed to adsorption on the support material. The influence of several reversed-phase supports on retention and peak symmetry has been studied. Little difference was found for uncharged acids, but retention and peak shape of the cations was dependent on the specific support. Also on the poly(styrene-divinylbenzene) copolymer PRP-1 cations gave tailing peaks. The results indicate that the surface of reversed-phase supports is heterogeneous. From this and other studies it can be concluded that only certain reversed-phase silicas, such as μ-Bondapak, are suitable supports for cationic solutes. In liquid-liquid chromatography polar solutes only obey a liquid-liquid distribution model if the liquid stationary phase molecules contains a hydrophobic group, as well as a polar function.
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  • 66
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fractional factorial experimental designs ; Ruggedness test ; Method validation
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    Topics: Chemistry and Pharmacology
    Notes: Summary Recently much attention has been directed to the validation of analytical methods. The level of validation will depend on the method application. If a method is developed for general use, for instance by different analysts, instruments or laboratories, then the effect of these changes need evaluation. This is normally referred to as ruggedness testing, where the limitations of the method to changes in the specified conditions are examined. This paper examines the use of Plackett-Burman fractional factorial experiment designs for ruggedness testing in high performance liquid chromatography (HPLC). The ability of these designs to identify confounding effects is applied to the stability indicating analysis of Salbutamol and its major degradation product, AH4045. The results show that confounding effects, proving extremely pertinent to HPLC, can be identified. The assay proved rugged to most tested changes although not to the use of column packing material from different manufacturers.
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  • 67
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    Chromatographia 25 (1988), S. 791-796 
    ISSN: 1612-1112
    Keywords: Gel permeation ; Column liquid chromatography ; Column switching ; Additives in cellulose acetate
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    Topics: Chemistry and Pharmacology
    Notes: Summary The capability of elution-elution multi-dimensional liquid chromatography was investigated. A “column scaling” approach was evaluated for the quantification of low-molecular-weight additives in cellulose acetate. A small-bore (1-mm i.d.) gel-permeation column was used to separate the higher-molecular-weight polymer from the lower-molecular-weight components. Once separated these additives were transferred to a C18 reversed-phase column via a switching valve. The reversed-phase system successfully separated and quantified individual additives. Analysis time for an ultraviolet inhibitor, Tinuvin®P, in cellulose acetate, including re-equilibration, was approximately 30 minutes. Both accuracy and precision were good. Precision over a three day period was about 1.5%.
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  • 68
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    Chromatographia 25 (1988), S. 811-814 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Separation of trimedlure isomers ; Medfly ; Ceratitis capitata
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    Topics: Chemistry and Pharmacology
    Notes: Summary Semi-preparative high-performance liquid chromatographic procedures on 5 μm silica were developed for the isolation of gram quantities of eight trimedlure isomers (trans: A, B1, B2, and C;cis: V, W, X, and Y) for comparative biological evaluation and NMR studies. Isolations were made from an eight-component 2∶1cis: trans-trimedlure mixture, a four-componentcis-trimedlure mixture, trimedlure-B2:X and trimedlure-C:W epimerization merization mixtures, a trimedlure-B1:Y:B2 mixture, and a trimedlure-A concentrate.
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  • 69
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand exchange ; On-Line preconcentration ; Opiate pentapeptide
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    Topics: Chemistry and Pharmacology
    Notes: Summary In order to study the occurrence of the opiate pentapeptide β-[D-Ala2,4, Tyr5] CM-5-NH2 in the 10−9–10−5 M concentration range, we have developed a new method consisting of extraction of the peptide from its buffered aqueous medium onto a reversed phase cartridge of 50 μL void volume, followed by on-line injection onto a Cu(II) modified silica gel column. The acetonitrile-rich mobile phase allows detection of the natural fluorescence of the peptide at the picomole level.
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  • 70
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    Chromatographia 25 (1988), S. 697-700 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micro columns ; Fluorometric detection ; Packed flow cell
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    Topics: Chemistry and Pharmacology
    Notes: Summary A packed flow cell was used for fluorometric detection in micro high-performance liquid chromatography. The flow cell consisted of fused-silica tubing packed with the same material as the separation column. A focusing effect of the stationary phase on the signal intensity was observed, leading to an improvement of the mass detection limit, as achieved by on-column detection.
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  • 71
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair chromatography ; Peak compression ; Remoxipride metabolite ; Conjugate
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    Topics: Chemistry and Pharmacology
    Notes: Summary FLA 908 was identified as a metabolite of remoxipride in human urine after enzymatic hydrolysis. The identity was proven by comparison of its retention time in LC and its UV and mass spectra to authentic FLA 908. The concentration of FLA 908 in human urine was determined using chromatographic conditions where a peak compression effect was obtained. This effect, giving an extremely narrow peak for FLA 908, made it possible to determine low concentrations of the compound in enzymatically hydrolyzed urine. The limit of quantitation was improved more than by a factor of 5 compared to conventional chromatography and the precision was good with a coefficient of variation of 〈5%. Less than 1% (0.44–0.91%) of the administered remoxipride dose was found to be excreted as conjugated FLA 908 while only trace amounts (≤0.01%) of nonconjugated FLA 908 were seen.
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  • 72
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair chromatography ; Valve switching ; Fluorouracil
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    Topics: Chemistry and Pharmacology
    Notes: Summary Fluorouracil has been analyzed with a reversed-phase ion-pair liquid chromatographic system applying PRP-1 as the stationary phase. A valve switching technique was applied for the separation of the analyte and some other chemotherapeutic agents. The described procedure gives a rapid screening for the analyte in urine and plasma samples without interferences from late eluting solutes. Biological samples are pretreated by means of a liquid-liquid extraction resulting in a recovery of about 52% for plasma and urine with minimum detectable amounts of about 5ng/ml. The sensitivity and the selectivity of the procedure allows the monitoring of fluorouracil in body fluids and subsequent pharmaco-kinetic studies of the fluoropyrimidine.
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  • 73
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    Chromatographia 22 (1986), S. 381-387 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Precolumn derivatisation ; Amino acid analysis ; Fluorenylmethyloxycarbonylchloride (FMOC)
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  • 74
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    Chromatographia 26 (1988), S. 234-236 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparative-scale separations ; Teicoplanin ; Structure determination
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    Topics: Chemistry and Pharmacology
    Notes: Summary Teicoplanin, a lipoglycopeptide antibiotic active against gram-positive bacteria, is produced as a complex mixture consisting of six major components and four chemically related minor cmmponents. Preparative HPLC was used to isolate small amounts of the pure minor components, in order to determine their structures. In the present paper the isolation procedures are presented, as well as the analytical HPLC conditions. The retention times of the minor components with respect to those of the more abundant compounds, permittedus to make hypotheses on their structures, which were then confirmed by NMR and FAB-MS investigations.
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  • 75
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    Chromatographia 23 (1987), S. 709-712 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polymer-based support ; Aldehydes ; Fluorescence detection
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    Topics: Chemistry and Pharmacology
    Notes: Summary The aldehydes were separated by reversed phase chromatography on a polymer-based support. Acid catalysis on the column was needed to obtain sufficiently fast equilibrium between acetaldehyde and its hydrate. Deuterium labeled acetaldehyde (D3) yielded complete separation from the nonlabeled compound, probably due to a difference in hydratization. Fluorescent products were obtained by reaction between the aldehydes and a mixture of ammonia and dimedone (5.5-dimethyl-1.3-cyclohexanedione). The fluorescence was detected at 460 nm after excitation at 390 nm. A reaction time of 42 seconds at 90°C in a knitted teflon capillary produced detection limits of 0.5 and 1 ng for acetaldehyde and formeldehyde, respectively. A method for preparation of a stable reagent with low background fluorescence is described.
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  • 76
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Penstemide and serrulatoloside
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    Topics: Chemistry and Pharmacology
    Notes: Summary Penstemide and serrulatoloside, two iridoids of similar molecular structure, were separated by stepwise gradient TLC in a straight-phase systems (silica-ethyl acetate+isopropanol) and by HPLC in a reversed-phase system (ODS-silica — water+methanol).
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  • 77
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    Chromatographia 27 (1989), S. 27-30 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; 1,ω-Di(alkoxy)-polysulphides ; Retention contributions
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    Topics: Chemistry and Pharmacology
    Notes: Summary The reaction of S2Cl2 with alcohols yields products, the reversed-phase liquid chromatograms of which are similar to those of dialkyl-polysulphides RSnR, i.e., they represent homologous series. Four of the products were identified via GC-MS as 1,ω-di(alkoxy)-polysulphides having the general structure ROSnOR. Retention contributions of alkyl groups R and sulphur atoms in the −Sn — chain are not much different from values observed with polysulphides. The effect of oxygen, however, is only about −100 index units per O atom, while in dialkyl ethers values of −500 units have been reported.
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  • 78
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    Chromatographia 26 (1988), S. 369-371 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Urinary trypsin inhibitors
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    Topics: Chemistry and Pharmacology
    Notes: Summary Human urine contains a family of trypsin inhibitors. Procedures for their purification and characterization involve laborious techniques and the conclusions are different in the identification of the separated compounds. We report results obtained by applying our RP-HPLC method to some procedures adopted by different authors.
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  • 79
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Biphenols ; Dihydroxyphenylpropanes ; Voltammetric detection ; UV photometric detection
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    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behaviour of mono- and dihydroxy derivatives of biphenol and bis(hydroxyphenyl)propanes was studied on chemically bonded C-18, CN-, phenyl, phenoxypropyl- and NH2 stationary phases and on silica gel. The effects of the mobile phase, i.e., of the methanol content, the ionic strength, pH and the contents of cationic and anionic ion-pairing agents on the retention data were investigated. In the reversed-phase systems, all the substances are satisfactorily separated except for 3- and 4-hydroxybiphenyl; these isomers can be separated on silica gel, using a mixture of heptane and propanol as the mobile phase. Sodium dodecylsulphate, present at concentrations higher than the critical micelle concentration (about 10−2 M, depending on the methanol content), causes a decrease in the retention times and an improvement in the separation. UV absorption spectra, calibration curves and the detection limit values were obtained at two wavelengths and at various salt concentrations in the mobile phase. Hydrodynamic voltammograms of the solutes were measured in a carbon fibre detector and the calibration curves and detection limit values were measured at the optimal voltage (+1.2 V/Ag/AgCl) as a function of the mobile phase composition. For most test substances voltammetric detection is two to three times more sensitive than UV detection. The combination of a UV and a voltammetric detector in series has been utilized to identify the products of microbial degradation of biphenyl.
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    Chromatographia 23 (1987), S. 109-111 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Normal and reverse phase ; Aldicarb ; Aldicarb sulfoxide ; Aldicarb sulfone
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    Topics: Chemistry and Pharmacology
    Notes: Summary Aldicarb, aldicarb sulfoxide, and aldicarb sulfone were chromatographed on an octyl-silica bonded-phase column and on an unmodified silica column using acetonitrile/water mobile phases. The elution order of the analytes from the silica column was different from that using the octyl-silica bonded phase and allowed confirmation of residues of aldicarb sulfoxide in citrus nectar. Isocratic elution of the unmodified silica column allowed rapid sample throughput.
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  • 81
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand-exchange chromatography ; Chiral bonded phase ; Racemate resolution ; Amino acids
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    Topics: Chemistry and Pharmacology
    Notes: Summary The resolution of racemates on chiral chemically bonded silica gel by high-performance ligand-exchange chromatography is described. The stationary phase was prepared by bonding (−) trans 1,2 cyclohexanediamine to silica gel through the coupling agent 3-glycidoxypropyl silane. The resolution of several α-amino acids and of compounds of pharmaceutical interest is reported.
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  • 82
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral recognition process ; Enantiomeric elution order ; Mobile phase modifiers
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    Topics: Chemistry and Pharmacology
    Notes: Summary Three enantiomeric solutes, a sulphoxide, a piperidine derivative and a methyl ester have been chromatographed on an HPLC chiral stationary phase (CSP) based upon cellulose-tribenzoate (Chiralcel OB-CSP). The mobile phases used in the study were composed of hexane modified with homologous series of primary, secondary and cyclic alcohols. Interesting reversals in enantiomeric elution order have been observed for 2-phenoxypropanoic acid methyl ester associated with changes in chain length or ring size of the alcohol mobile phase modifier. The results of the study suggest that at least two chiral recognition mechanisms operate on the OB-CSP and point out the importance of acquiring elution order data in all studies involving chiral stationary phases.
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  • 83
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    Chromatographia 27 (1989), S. 101-104 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bromo/iodosubstituted thyronines ; Mobile phase optimization ; Radioimmunoassay detection
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    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase high performance liquid chromatographic method on C-18 bonded silica is described for the separation of trisubstituted iodo/bromothyronines, which exert thyroid hormone activity. The composition of the mobile phase has been systematically optimized resulting in a ternary mixture of methanol/acetonitrile/water acidified with trifluoroacetic acid. The applicability of ultraviolet absorption detection, amperometric detection and off-line radioimmunoassay was investigated. The latter method allows detection of the different iodo/bromothyronines down to 40–120 ng/l mobile phase; this sensitivity is high enough for application to thyroid hydrolysates in order to clarify the question as to whether bromine can substitute iodine in the biosynthesis of thyroid hormones.
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    Chromatographia 27 (1989), S. 113-117 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention contribution of nitrogen ; Effect on methylene and sulphur chains
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    Topics: Chemistry and Pharmacology
    Notes: Summary The reaction of secondary amines R2NH with disulfur dichloride S2Cl2 in dichloro methane yields mixtures of bis-dialkylamino polysulphides R2N−Sn−NR2 with sulphur chain lengths varying from ns=2 to 14. The S chains are believed to be non-branched. The compounds form homologous series in each of which sulphur atoms give a constant contribution to retention. The sulphur retention index depends slightly on the carbon number in the terminal alkyl groups R. The presence of nitrogen lowers retention. The index increment of N is ca. −160 units, which is distinctly less negative than values found in alkylamines.
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  • 85
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion chromatography ; Fast atom bombardment-MS ; Peptic haemoglobin hydrolysate
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    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the ready identification of any peptide isolated from a complex peptic haemoglobin hydrolysate produced on the pilot-plant scale. A combination of size exclusion and reversed-phase, high-performance liquid chromatography have proved to be a useful strategy for fractionation of such a mixture. This technique enabled pure peptides from the total hydrolysate to be obtained. Amino acid analysis and fast atom bombardment mass spectrometry provided the accurate composition and molecular weight of any isolated peptide. Molecular weights are compared with those deduced from size-exclusion chromatography (SEC) and the usefulness of SEC is discussed. The procedure described in this study will be useful for acquiring a better knowledge of such an hydrolysate and could be extended to other crude protein digests.
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    Chromatographia 27 (1989), S. 194-200 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dissociation constants ; Potentiometric titration ; 2,4-Dimethylthiazole ; Trimethylpyrazine ; Methyl anthranilate
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    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase liquid chromatography on two stationary phases—octadecylbonded silica Partisil ODS-3 and polystyrene-divinylbenzene resin PRP-1—and potentiometric titration in the water/methanol mobile phase were investigated in order to determine the dissociation constants of three weakly basic aroma compounds, namely trimethyl pyrazine, 2,4-dimethyl thiazole and methyl anthranilate. The data obtained from both methods are quite consistent and compare favourably to values found in the literature.
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    Chromatographia 27 (1989), S. 292-296 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Selenium(IV)-tellurium(IV) separation ; Flow-through coulometric detector
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    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of selenium and tellurium has been investigated with two different reversed-phase chromatographic methods, using P-350 (methyl-bi-isooctyl phosphate) and TBP (tributyl phosphate) as the stationary phases. HCl, HBr, NaCl and NaBr were employed as mobile phase components in both methods. The results suggested that the separation mechanism corresponds to the formation of TeCl (or TeBr) and P-350H (or TBPH) ion associate. A coulometric flow-through detector was applied to determine Se(IV) and Te(IV). Complete separation and quantitative determination of Se and Te could be achieved in 10 minutes.
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    Chromatographia 27 (1989), S. 371-377 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alkyl-bonded silica gel ; Enthalpy ; Van der Waals volume
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    Topics: Chemistry and Pharmacology
    Notes: Summary Starting from silica gel with a purity of 99.999%, octadecyl-(ODS), octyl-(C8) and propyl-(C3) bonded silica gels were synthesized, and end-capped by trimethyl groups. The pore size was 150 Å and the specific surface area was 320 m2/g. The ODS and C8 silica gels were stable in both acidic and basic solutions. The selectivity of these bonded-silica gels was examined from the difference of the retention behavior of alkanes (Al−Al), alkylbenzenes (Ph−Al), alkylalcohols (Al−OH) and polyaromatic hydrocarbons (PAH) in aqueous acetonitrile. On these packings the log k′ values decreased in the order Al−Al〉Ph−Al〉PAH〉Al−OH. Furthermore, the chromatographic behavior of these compounds was measured on polymer-coated octadecyl-bonded silica gel (CAP) and octadecyl-bonded vinyl alcohol copolymer gel (ODP). The selectivity was verified from the value of R* of these compounds: $$R = R_v + R^* $$ where R is the retention time, and Rv is the retention time of an alkane having the same Van der Waals volume as the analyte. The R* values indicated that this ODS had more selectivity than C8 and C3, however R* on C8 showed a very good correlation with R* on C3. Their retention behavior on CAP was similar to that of ODS, however, their capacity ratios measured on CAP were smaller than those on ODS. The ODP has selectivity for the retention of aromatic compounds, because PAHs were retained strongly on this column.
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  • 89
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alternaria mycotoxins ; Food analysis ; Electrochemical detection
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    Topics: Chemistry and Pharmacology
    Notes: Summary The electroactivity of majorAlternaria mycotoxins has been explored in order to devise a liquid chromatographic-electrochemical detection (LC-EC) method for the determination of these toxic metabolites in fungal cultures and in naturally contaminated foodstuffs. Alternariol, alternariol methyl ether, altertoxin-I and altertoxin-II have been found to be electroactive and could be detected at sub-nanogram levels. Advantages and limitations of dual electrode (screen mode) coulometric detection and single electrode amperometric detection are presented and discussed. The feasibility of electrochemical detection in gradient elution liquid chromatography as well as its applicability to the analysis of contaminated foodstuffs is demonstrated.
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    Chromatographia 27 (1989), S. 431-435 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; UV diode array detection ; Electro chemical detection ; Herbicides
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    Topics: Chemistry and Pharmacology
    Notes: Summary An automated procedure is described for simultaneous UV detection at three different wavelengths and electro chemical detection in series of some residual herbicides. UV spectra of nine compounds of different compound groups are presented. Liquid-liquid extraction with dichloromethane and an enrichment of about one thousandfold has been used. Recovery rates after enrichment and detection limits of four s-triazine, three phenyl urea herbicides, metazachlore and metamitrone in river and drinking water are shown. It is concluded that the herbicides examined can be detected at levels between 10ng l−1 and 50ngl−1, without the necessity of derivatisation or clean-up processes.
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    Chromatographia 27 (1989), S. 449-454 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion exchange and affinity columns in series ; Porcine pancreatic enzymes ; Trypsin and elastase
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    Topics: Chemistry and Pharmacology
    Notes: Summary In order to separate and purify some of the enzymes contained in porcine pancreas, operation of an ion-exchange column in series with an affinity column has been used. The enzymes dealt with possess very similar molecular weights, isoelectric points and active sites. Hence they are difficult to separate and purify by traditional separation and/or purification methods. CM-Sepharose anion-exchange resin adsorbs elastase and trypsin at low pH (4.5) and desorbs them at high pH (9.0) and high ionic strength. Chitin-CHOM affinity adsorbent adsorbs trypsin at high pH (8.0) and desorbs it at low pH (2.5). By virtue of this complementary relationship two chromatographic columns were connected in series for facilitating the separation and purification of elastase and trypsin from porcine pancreas. The result showed that the specific activities of elastase and trypsin had been increased 16 and 22 fold respectively.
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    Chromatographia 28 (1989), S. 27-30 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Atmospheric ammonia ; m-Toluamide derivative ; Annular denuder
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    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and reliable method for routine measurement of ammonia in ambient air is described. It is based on the collection of ammonia on H3PO3-coated annular denuders and its subsequent derivatization withm-toluoyl chloride (MTC) in alkaline acetonitrile. The resultingm-toluamide is determined by reversed phase HPLC with UV detection at 230 nm. The limit of dotection is about 0.3μg m−3 for NH3 in air samples collected at 151 min−1 for one hour.
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    Chromatographia 28 (1989), S. 39-44 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thermus aquaticus ; Ribosome ; 50S and 30S subunit proteins ; Gel electrophoresis
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    Topics: Chemistry and Pharmacology
    Notes: Summary The ribosomal 50S and 30S subunit proteins (r-proteins) ofThermus aquaticus have, for the first time, been characterized by size exclusion chromatography (SEC) and by reversed phase high performance liquid chromatography (RPC). To ensure that the best resolution in the RPC was obtained. the elution conditions, such as gradient time, flow rate, temperature, ionic strength of the eluent and the type of stationary phase were optimized. Correlation between experimentally found retention times and those predicted by DryLab G was better than 0.7% over 30 peaks. Protein fractions from RPC runs were desalted and processed by gel electrophoresis so that the ribosomal proteins could be identified by their position on SDS-polyacrylamide gels. The enhanced speed and quality of separation which has been achieved in this study is expected to bring advantaces in experimental work with ribosomal proteins as well as with other biopolymers. In our case the high resolution technique provides a basis for the preparation of a collection of individual ribosomal protein components for future rRNA-protein interaction studies.
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  • 94
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    Chromatographia 28 (1989), S. 19-23 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparation of stationary phases ; Polymer coated stationary phases ; Polymer-octyl bonded phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polymethyloctylsiloxane-coated stationary phases have been prepared for liquid chromatography, by thermal reaction. The influence of the reaction conditions on retention and efficiency of test substances with different structures has been discussed. The materials have good stability in both acidic and basic eluents.
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  • 95
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    Electronic Resource
    Springer
    Chromatographia 28 (1989), S. 89-91 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrophoresis ; Comparison of HPLC and electrophoresis ; Proteins, peptides and amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Protein structure analysis is an indispensible tool in modern biological research. However, the isolation of a protein or the separation of peptides in a form suitable for sequence analysis is a considerable technical challenge. The two predominant separation methods in protein biochemistry are chromatography and electrophoresis. In this paper the position, advantaged and disadvantages of both HPLC and electrophoresis for the separation of amino acids, peptides and proteins in protein structure analysis are discussed.
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  • 96
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detection ; Pseudouridine ; Creatinine ; Urine analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The anodic behaviour of pseudouridine a modified nucleoside proposed as tumoral marker, has been studied at a mercury electrode. A method for its determination in urine samples by liquid chromatography with indirect anodic polarographic detection has been developed. The method is simple, highly selective and permits the direct injection of urine after dilution (1∶20) with mobile phase. Creatinine, which also gave an anodic response on mercury, could be simultaneously determined and used as an “internal standard” for Psi. This allowed the pseudouridine/creatinine ratio determination in a single run on the same specimen and the use of urine samples collected randomly instead of the 24h collection. The within-day RSD% for pseudouridine/ creatinine peak areas ratio was 3.4%.
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  • 97
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    Springer
    Chromatographia 28 (1989), S. 565-568 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; New bonded phases ; Alumina ; Protein separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several reactions are tested for the chemical modification of alumina. These include the following: chlorination of the surface hydroxyls followed by reaction with an organolithium compound; chlorination of the surface hydroxyls followed by reaction with a Grignard reagent; chlorination of the surface hydroxyls followed by reaction with an amine; chlorination of the surface hydroxyls followed by reaction with an alcohol; direct reaction of the alumina with an organochloroalane and direct reaction of the alumina with an alcohol. Only the first reaction gave a product which contained enough bonded organic material to be easily detected by FTIR. Preliminary stability tests show that the product of the first reaction retains the bonded organic material when exposed to nonpolar and polar organic solvents as well as aqueous solutions of pH 1.0, 7.0 and 12.0. Chromatographic testing establishes reversed-phase behavior for alkylarylketones as solutes and the bonded phase displays good biocompatibility for a series of protein standards.
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  • 98
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Adenosine phosphates ; Adenosine phosphate degradation products ; Innervated frog muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Adenosine mono-, di- and triphosphates, inosine monophosphates, adenosine, inosine and hypoxanthine were separated in a single run by high-performance liquid chromatography with UV detection. AC-18 reversephase column was used. An isocratic elution with 100mM phosphate buffer (KH2PO4) pH6.5 and 1.2% methanol, followed by a 5 minute linear gradient up to 15% methanol after the 10th minute was performed during each run with a flow rate of 1.25ml/min. The time required for each analysis was 25 minutes. The detection limit for each substance ranged from 3 to 5 pmol. All the substances under study were detected in the incubation medium when adenosine triphosphate was exogenously applied to the innervated frog sartorius muscle.
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  • 99
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 28 (1989), S. 34-38 
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Methylisothiazolones ; Preservatives ; Analysis of cosmetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Antimicrobially active formulations based on 2-methyl-3(2H)-isothiazolone and 5-chloro-2-methyl-3(2H)-isothiazolone (Kathon CG, Euxyl K 100) are incorporated into manufactured cosmetics as preservatives. In this paper we report on the analysis of these active components by means of liquid chromatography. It is conventional for the original methylisothiazolone components in cosmetics to be analyzed by reversed phase high-performance liquid chromatography after column chromatographic separation and flash chromatographic purification. In our new analytical method the methylisothiazolones are converted into the respective β-thiosubstituted acrylamide derivatives, which are ionic substances, with the help of the nucleophilic reagent hydrogensulfite. An ion pair high-performance liquid chromatographic method has been developed for the separation and quantification of these derivatives.
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  • 100
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Molecular interactions ; Association effects ; Analyte solvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The linear Jaroniec equation has been utilized for the description of chromatographic systems in which the test substance molecule is solvated by the solvent molecules. A possibility of the formation of multimolecular solvates in the bulk phase has been confirmed. The measurements were made using liquid adsorption chromatography with ternary mobile phase.
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