摘要:

Moving bed chromatography, and simulated moving bed chromatography has been known for over 50 years, but has recently become important in the isolation of pure substances where the components are very similar, as in the case of enantiomers and in the isolation of substances which would be difficult or impossible by other means. The first example of moving bed chromatography was in the separation of pure acetylene from methane oxidation products, reported in 1956. Subsequently, in 1958, the separation of pure benzene from coal gas was described using gas liquid chromatography and a moving bed system.

ISSN:1082-6076    

DOI:10.1081/JLC-100102368

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Employing density data reported for a range of tetrahydrofuran-water mixtures, measured at different temperatures, the tetrahydrofuran-water association constant was calculated at each temperature, employing previously established procedures. The standard free enthalpy and entropy of association were then determined from the linear relationship that exists between the logarithm of the association constant and the reciprocal of the absolute temperature. It is shown that the standard free enthalpy is very high for simple association, viz., 1.642 Kcal/mol, and the standard free entropy of distribution was3.00 cal/mol. These values indicate strong association and the relative low standard free entropy shows a comparatively small change in molecular freedom after association.This suggests that the solvents are also probably strongly associated with themselves when not associating with each other.

ISSN:1082-6076    

DOI:10.1081/JLC-100102369

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A rapid, specific, sensitive, and reproducible high performance liquid chromatography-mass spectrometric assay has been developed for the quantitation of five sulfur-containing non-steroid anti-inflammatory drugs (NSAIDs), namely, celecoxib (Cel), piroxicam (Per), rofecoxib (Rof), sulindac (Sul), and tenoxicam (Ten), in available tablets and capsules. The examined compounds were extracted from the dosage forms with methanol and chromatographed on a Shim-Pack column using a mobile phase of acetonitrile and 1% acetic acid solution in a ratio 4:1 (Cel, Per, Sul, Ten) or acetonitrile and 20 mM ammonium acetate buffer solution (4:1) (Rof). The analytes were determined by an ion-trap mass spectrometer (Finnigan Mat) using APCI as an ionization process. The eluted compounds were detected either in the positive single ion monitoring mode at m/z 382.0, 332.0, 357.0, 338.4 (Cel, Per, Sul, Ten), or in the negative single ion monitoring mode at m/z 313.2 (Rof).

ISSN:1082-6076    

DOI:10.1081/JLC-100102370

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

8-Hydroxyquinoline, methanol, and Triton X-100 were first used together in the extraction of metal ions by supercritical fluid. In the new system, the effects of pressure, temperature, and the volume of supercritical CO2used on the efficiency of supercritical fluid extraction (SFE) were systematically investigated. The recovery of Cu2+was only 17.7% by pure supercritical CO2while the recovery increased significantly (83.6%, RSD=3.64%, n=5) with the addition of a suitable amount of methanol (v/v=5%).

ISSN:1082-6076    

DOI:10.1081/JLC-100102371

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Human serum albumin was purified by size-exclusion liquid chromatography. The glycated albumin in the effluent was selectively measured by a post-column reaction detector. The selective reaction mechanism is to measure the amount of Amadori form of glycated albumin. According to the Maillard reaction, glycosylated amines are rearranged to Amadori form ketoamines which can produce superoxide in strong alkaline solution, and this superoxide produces chemiluminescence with lucigenin. The chemiluminescence intensity was related to the concentration of glycated albumin in albumin while the fluorescence intensity was the same.

ISSN:1082-6076    

DOI:10.1081/JLC-100102372

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The aim of the current work is to discuss a quick method for the isolation and enrichment of denatonium benzoate from low-solidification fluids applied for cooling of internal-combustion engines (liquids based on ethylene and propylene glycol). This method, i.e. solid phase extraction (SPE), can be coupled with other techniques, mostly high performance liquid chromatography in reversed phase mode (RP HPLC).

ISSN:1082-6076    

DOI:10.1081/JLC-100102373

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Plasma homocysteine level has been linked with the risk of occlusive vascular disease. Due to the presence of multiple forms of homocysteine, with the majority found as protein-bound homocysteine, and the interchanges among non-protein-bound homocysteines, the concern of analytical reliability for total plasma homocysteine has been raised. In this research, plasma samples are reduced by dithiothreitol to break disulfide linkages.

ISSN:1082-6076    

DOI:10.1081/JLC-100102374

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A liquid chromatographic-atmospheric pressure ionization ionspray method for the determination of anatoxin-a, microcystin desmethyl-3-RR,LR, RR and YR in water, is described. The method involves no sample pre-filtrationto separate cyanobacteria from the water. The water sample was added to sodium1-heptanesulfonate and cleaned-up using LMS solid phase extraction columns.The method is simple, specific, and requires small quantities of chemicalreagents. The lower limits of quantification were 0.4 μg/L for anatoxin-a,microcystin desmethyl-3-RR and RR, and 0.5 μg/L for LR and YR.

ISSN:1082-6076    

DOI:10.1081/JLC-100102375

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A reversed-phase high performance liquid chromatography method, previously optimized, was applied to determine the soybean protein content in commercial soybean liquid milks. Quantitation of soybean proteins was first performed by using soybean protein isolate as external standard. Although this standard seemed suitable for the quantitation of soybean proteins in some soybean liquid milks, for those soybean milks directly prepared from whole soybeans, a best estimation of the soybean protein content was obtained by using soybean flour as external standard.

ISSN:1082-6076    

DOI:10.1081/JLC-100102376

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A simple, rapid, and stability-indicating HPLC method has been developed for the determination of isoxsuprine in the presence of its degradation products. Acetonitrile: potassium dihydrogen phosphate (0.01 M solution) adjusted to pH 2.2 ± 0.1 with phosphoric acid (18:82 v/v), was used as the mobile phase, at a flow rate of 2.5 mL/min.

ISSN:1082-6076    

DOI:10.1081/JLC-100102377

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor