摘要:

Diltiazem (DTZ) is an anti-hypertensive and anti-anginal agent which is also used clinically as a metabolic inhibitor to reduce cyclosporin-A metabolism. The present communication describes an HPLC/UV method for measuring DTZ and 3 of its major metabolites. This method has a LOQ below 2.5 μg/L and within run CV's ranging from 11.3 to 1.9% at concentrations of 2.5 and 100 μg/L, and between-run CV's ranging from 10.5 to 4.9% at concentrations of 75 and 350 μg/L, respectively. The method has been applied successfully to 11 renal transplant recipients taking a variety of other drugs.

ISSN:1082-6076    

DOI:10.1080/10826079608014024

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We have developed a sensitive, reliable and highly specific method for the determination of ochratoxin A (OA) in cereals and animal feed. The samples were extracted in acidified acetonitrile and, they were then thoroughly purified by a new procedure combining a pH-controlled liquid-liquid partition with a strong anionic exchange solid-phase extraction. Both RP-TLC and RP-HPLC methods for semi-quantitative and quantitative determination have been described respectively, together with a RP-HPLC confirmation procedure, via conversion to OA-methyl ester. The TLC and HPLC determination limits were 8.0 ng/g and 0.10 ng/g respectively. The mean recovery from spiked samples was 95%.

ISSN:1082-6076    

DOI:10.1080/10826079608014025

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A new, simple, reverse phase, and highly reproducible HPLC-UV method that has all the comprehensive features of good column, mobile phase, internal standard and extraction has been developed for the assay of clozapine (CLZ), norclozapine (NCLZ) and clozapine-N-oxide (CLZNO) in human serum. The method is very easy to adapt, overcomes the problems of earlier methods and is very economical. Amoxapine is the internal standard. All three analytes are extracted from alkaline serum using ethyl acetate and the absolute extraction efficiency is ∼95%. The UV detector is set at 230 nm. The mobile phase is a mixture of phosphate buffer (0.05M, pH 2.7), acetonitrile and methanol (62:20:18 v/v) and contains 2.5 mL triethylamine per liter of solution. The detection limit of the method is 2 ng/mL for CLZ and NCLZ and 4 ng/mL for CLZNO. The mean CV for the method is 5%.

ISSN:1082-6076    

DOI:10.1080/10826079608014026

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A mixture of polycyclic aromatic hydrocarbons and azaarenes was used to test C18/cyano mixed phases prepared by mechanical mixing of silica-based bonded phases for one-dimensional T.L.C. It was shown that for a normal phase polarity mechanism, the modulation in polarity of the stationary phase, obtained by simple variation of the percentage of the cyano phase, contributed to an improvement in the resolution of the mixture.

ISSN:1082-6076    

DOI:10.1080/10826079608014027

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

High performance liquid affinity chromatography (HPLAC) is a powerful method for purification and analysis of biological compounds. It combines the speed and the efficiency of high performance chromatography with the selectivity of affinity chromatography methods. The selectivity depends, first, on the nature of the ligand used; this latter must exhibit a specific binding affinity towards the product to purify; second, it depends on adsorption and desorption processus that improve, or not, the protein affinity for the ligand.

ISSN:1082-6076    

DOI:10.1080/10826079608014028

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A high capacity process is described for the preparative purification of a soluble form of bovine lung angiotensin I-converting enzyme by affinity and size exclusion chromatography. The affinity purified enzyme was solubilized by tryptic attack for 1 h at 300C and separated by Sephacryl S-300 HR chromatography. A recovery of 68% was obtained. The purification procedure described here, enables one to obtain 27 mg of enzyme with a specific activity of 26 min−1mg−1from 1 kg of bovine lung. Molecular mass of native soluble ACE form was obtained by size-exclusion high performance liquid chromatography. Molecular mass of membrane-bound enzyme and the ACE form solubilized with trypsin, was found to be 170 kDa and 160 kDa, respectively, using disc gel electrophoresis in the presence of sodium dodecyl sulfate.

ISSN:1082-6076    

DOI:10.1080/10826079608014029

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Chromatographic studies on the effect of exposure of polypyrrole coated stationary phases to redox reagents have been carried out. Polypyrrole containing chloride or dodecylsulfate as counterion was chemically synthesized and coated onto silica particles and packed into a chromatographic column. A series of standard compounds was used as the molecular probes. Changes in the chromatographic properties of polypyrrole as the result of the exposure to redox reagents were compared with those obtained by electrochemical treatment.

ISSN:1082-6076    

DOI:10.1080/10826079608014030

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Empirical equations were used to predict the retention behaviour of a group of twenty-seven dihydropyridines in Micellar Liquid Chromatography with hybrid eluents on an octylsilica column. A theoretical model was also used to study their retention mechanism. Hexadecyltrimethylammonium bromide and sodium dodecyl sulphate were used as surfactants in the mobile phase and as organic modifiers n-propanol and n-butanol were employed.

ISSN:1082-6076    

DOI:10.1080/10826079608014031

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An improved high performance liquid chromatographic method was developed to determinate the active triacylglycerol principles ofPanax pseudo-ginsengWall. var. notoginseng Hoo & Tseng extracts. Chromatographic analysis is achieved on an isocratic system consisting of a polymeric reverse phase C18column with a mobile phase of acetonitrile-methanol (50:50, v/v) to elute the trilinolein and triolein. The eluted triacylglycerol are detected at 205 nm. The linear calibration range was 0.5–20 and 20–500 μg/mL for trilinolein and triolein, respectively. The detection limit was 0.1 μg/mL for trilinolein and 10 μg/mL for triolein. It was found that n-hexane extracts ofPanax pseudo-ginsengWall. var. notoginseng Hoo & Tseng contained 0.21 ± 0.021 mg/g of trilinolein. However, triolein was not detectable in the same herbal extract.

ISSN:1082-6076    

DOI:10.1080/10826079608014032

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A nickel-chromium (80:20) alloy is employed as electrode material in the amperometric detection of underivatized amino acids in flow injection and high performance liquid chromatographic experiments. Cyclic voltammetric results show that amino acids are oxidized by a surface catalyzed process, proposed to involve Ni(III) oxyhydroxides, which are formed on the electrode surface at approximately 0.43 V (Ag/AgCl reference electrode) in 0.10 N NaOH. The hydrodynamic voltammograms of different amino acids show current plateaus at potentials above ca. 0.48 V. Preliminary HPLC experiments show that the nickelchromium alloy is useful for the amperometric detection of underivatized amino acids following anion exchange separations.

ISSN:1082-6076    

DOI:10.1080/10826079608014033

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor