摘要:

A novel reversed phase chromatography packing to be used for analytical protein separations is described. A macroporous silica support was bonded with diethoxymethylvinyl silane, and then copolymerized with hydroxyethyl methylacrylate and divinylbenzene to produce tailored stationary phase. This packing has high resolution and stability in extent pH range. It was characterized through the separation of two model protein mixtures, the first one containing lysozyme, cytochrome C, β-lactoglobulin, chick egg albumin, ribonuclease and pepsin (porcine mucus), the second mixture containing insulin (two kinds), ribonuclease, lysozyme, serum bovine albumin. Such manipulations of proteins' elution profile are achievable at run times of less than 15 minutes. It is suggested that the macroporous silica-based polymer-bonded packing is a better alternative for the biopolymer separation.

ISSN:1082-6076    

DOI:10.1080/10826079808001232

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Quantitative Structure Retention Relationships (QSRRs) of disubstituted N-benzylideneanilines are studied in normal phase liquid chromatography. Structural descriptors for each solute are calculated. Among the descriptors, four are retained to establish the QSRRs. The first descriptor, the dipolar moment is the most important parameter governing the retention, as it represents more than 90% of the log(k′) variation. The influence of three electronic descriptors, ionization potential and Hammett's constants σXand σY, is emphasized by the comparison of the QSRRs obtained.

ISSN:1082-6076    

DOI:10.1080/10826079808001233

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

HPLC with ultraviolet detection and wavelength programming was used to determine nineteen polycyclic aromatic hydrocarbons (PAH) in airborne diesel exhaust particulates. Eleven of these PAHs are included in the priority pollutants list of the US Environmental Protection Agency. Separation of PAHs is made with 5-μm polymeric C18column. The possibility of selecting the optimum wavelengths for each PAH gives the advantages of improved selectivity and increased sensitivity. Detection limits ranging from 0.1 to 0.2 ng are reached for most PAHs. Samples were soxhlet extracted and different organic solvents were compared.

ISSN:1082-6076    

DOI:10.1080/10826079808001234

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A reversed phase liquid chromatographic method was developed for the simultaneous determination of carboxylic acids and phenolics in white wines. The samples, diluted, were injected onto a Spherisorb ODS-2 column with a gradient of sulfuric acid (pH 2.5) / methanol as mobile phase. A diode array detector was used which was set at 210nm for carboxylic acids and altered to 278nm, during the run, for phenolics and sorbic acid. The identification of compounds was based on retention time, co-chromatography and UV spectrum. Some clean-up methods (sep-pak C18and an ion exchange column) were tested and did not improve the results.

ISSN:1082-6076    

DOI:10.1080/10826079808001235

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A modified cleanup procedure of 25-(OH)-vitamin D3from a previous method based on the use of C18and Si cartridges is proposed. The monitoring of the optimisation study was carried out by individual separation of the target analytes by HPLC and UV-detection. The improvement of the original procedure allows a dramatic reduction of plasma especies, which results in a more clean chromatogram in which other two hydroxymetabolites of vitamin D3(namely, 24-R,25-(OH)2-vitamin D3and 1-I,25-(OH)2-vitamin D3) can be determined. A closer to quantitativeness recovery of the target analytes (at least 4 times higher than in the original method) is achieved.

ISSN:1082-6076    

DOI:10.1080/10826079808001236

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A high performance liquid chromatographic (HPLC) method with spectrophotometric detection is presented for the assay of undecylenic acid, undecylenates (calcium, zinc), and the combination undecylenic acid-zinc undecylenate in commercial antifungal products. To enhance detection, an acetone solution of the sample preparation and sodium octanoate, the internal standard, was derivatized with 4′-nitrophenacyl bromide in the presence of triethylamine at 50°C for 30 min. An aliquot of the reaction mixture was directly analyzed on a Microsorb-MV C8column, with methanol-acetonitrile-water (50:30:20) as the mobile phase, and detection at 265 nm. At a flow rate of 1.6 mL/min, baseline resolution of the mixture of 4′-nitrophenacyl esters was attained in less than 7 minutes.

ISSN:1082-6076    

DOI:10.1080/10826079808001237

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A method for the content determination of felodipine from tablets using accelerated solvent extraction (ASE) was developed. Acetonitrile, methanol and a mixture of the two (2:1, v/v) were evaluated as the extraction solvents, at two different temperatures, 50°C and 100°C, for ground tablets. Acetonitrile gave the fastest extraction and methanol the slowest at both temperatures. No difference in extraction efficiency was observed between the two temperatures. To minimize sample handling, extraction of whole tablets was performed using the same parameters as for the ground tablets. 100°C gave higher recoveries than 50°C.

ISSN:1082-6076    

DOI:10.1080/10826079808001238

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A method using ion chromatography (IC) for the analysis of ferrous (Fe2+) and ferric (Fe3+) ions in soil extracts has been developed. This method uses an ion exchange column with detection at 520 nm after post-column derivatization. Selectivity is achieved by using an anionic chelating agent, pyridine-2,6-dicarboxylic acid, to form anionic complexes with ferric and ferrous ions. Using this method, both ferric and ferrous ions can be analyzed directly and simultaneously. The soil extractions were carried out with both 0.5 M hydrochloric acid (HCl) and 0.36 M oxalate under anaerobic conditions. Ferric and ferrous ions were stable in either 0.5 M HCl solution or deionized water at pH ∼ 1.7 when stored outside of a glove box. Ferrous ion was readily oxidized to ferric ion in aqueous solutions at pH values above 4.0 and in 0.36 M oxalate solutions at all pH values.

ISSN:1082-6076    

DOI:10.1080/10826079808001239

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The kinetics behaviour, activation parameters of thermal isomerization of meoisomer of diethyl 2,3-dicyano-2,3-diphenylsuccinate (1) in the aromatic compound solvents are investigated by external standard methods with HPLC at different temperatures of 90°C, 100°C, 110°C and 120°C, under protection of nitrogen gas. The relative error and the standard deviation of the quantitative analysis are less than ± 0.65% and 0.35, respectively. The experimental results show that both equilibrium constant K and standard free energy ΔG0of thermal isomerization reaction of compound1in different solvents are insensitive to the reaction temperature and the kinds of solvents.

ISSN:1082-6076    

DOI:10.1080/10826079808001240

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

An indirect reverse phase HPLC method to monitor low level impurities in an acyl halide, 3-phenylpropionyl chloride, is described. The method involves derivatization with aniline to form a stableN-anilide derivative followed by HPLC analysis. The selection of the derivatizing agent aniline was based on achieving similar detector responses for impurities relative to the 3-phenylpropionyl chloride. The method described is rugged, selective, and sensitive and provides an excellent way to assess the quality of acyl halides.

ISSN:1082-6076    

DOI:10.1080/10826079808001241

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor