摘要:

A hydrophobic interaction HPLC method was developed and validated for the analysis of human growth hormone (hGH) preparations. Separations were carried out on a TSK-Phenyl 5PW column using a descending linear gradient of 100% 1M ammonium phosphate dibasic/n-propanol (99.5:0.5), pH 8.0 to 100% 0.1M sodium phosphate/n-propanol (97.5:2.5), pH 8.0 over 30 minutes. The method proved highly reproducible for retention times, peak areas and peak heights, and the detector response for the main peak was linear between 1 and 1000 μg hGH/mL. Under these conditions, several hGH variants were resolved from the main hGH peak. A number of hGH preparations including the first WHO International Standard for hGH of pituitary origin and the new International Standard for hGH of recombinant origin were analysed.

ISSN:1082-6076    

DOI:10.1081/JLC-100101720

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A sensitive and enantioselective method for the determination of the dihydropyridine calcium antagonist manidipine in human plasma was developed by high performance liquid chromatography (HPLC). The method involves a rapid and simple extraction in human plasma based on C8 bonded-phase extraction, and extraction samples were purified and concentrated on the C1 pre-column by using the column-switching technique.(+)-Manidipine, (−)-manidipine and (+)-barnidipine as an internal standard were detected by ultraviolet detection at 254 nm, and enantiomers of manidipine were quantitatively separated by HPLC on a Sumichiral OA-4500 column, containing chemically modified Pirkle-type stationary phase. Calibration graphs were linear for each concentration of enantiomer from 1.0 to 25 ng/mL and the detection limit in human plasma was 0.5 ng/mL for each enantiomer. The recoveries of (+)-manidipine and (−)-manidipine added to plasma were 93.6%-99.3% and 91.5%-99.1%, respectively, with coefficients of variation of less than 9.5%, respectively.

ISSN:1082-6076    

DOI:10.1081/JLC-100101721

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This paper is an experimental contribution to the optimization of ovalbumin elution in RP-HPLC with a C4 support. The effects of TFA concentration, gradient duration, flow rate, and the nature of the solvent were studied using an experimental design. The results highlighted the major role of TFA concentration in the recovery yield of ovalbumin, with an optimum concentration range which is very narrow and much lower (0.025 %) than the levels usually applied (0.1 %). In this respect, ovalbumin seems to behave in a specific way. Among the four solvents tested, i.e. acetonitrile, isopropanol, ethanol, and a mixture of these three, the first one is definitely the most satisfactory in the area of recovery yield and efficiency. By modifying the elution conditions alone, the recovery yield of ovalbumin may range from 50 to 85 %.

ISSN:1082-6076    

DOI:10.1081/JLC-100101722

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

High performance liquid chromatography was employed to simultaneously determine the contents of six bioactive marker substances (cimifugin,prim-O-glucosylcimifugin, atractylon, atractylenolides I, II and III) in Yu-Ping-Feng-San. The separation was performed on a LiChrospher 100 RP-18e column by gradient elution with acetonitrile-water (v/v) (0 min, 16:84; 15 min, 20:80; 20 min, 50:50; 35 min, 55:45; 40 min, 75:25; 45 min, 80:20; 65 min, 85:15) as the mobile phase at a flow-rate of 1.0 mL/min, with detection at 220 nm or 277 nm. Benzophenone was used as the internal standard and six regression equations revealed linear relationships between the peak-area ratios (marker substances/internal standard) and concentrations. The repeatability and reproducibility (relative standard deviation) of the method were in the ranges of 0.03–1.07% and 0.13–1.21%, respectively.

ISSN:1082-6076    

DOI:10.1081/JLC-100101723

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A method of analysis using high performance liquid chromatography (HPLC) was developed for the separation and quantitation of the metabolites of stevioside: steviol-16,17α-epoxide, 15α-hydroxysteviol, steviolbioside, isosteviol, and steviol. The separation was carried out on a reversed-phase C18 Nova-Pack column with gradient elution of acetonitrile/water mixture. The applicability of the method was demonstrated in the detection and separation of stevioside and its metabolites found in blood, feces, and urine of hamsters after ingestion of stevioside.

ISSN:1082-6076    

DOI:10.1081/JLC-100101724

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Efficiency of transient supramolecular enantioselective recognition processes during direct, isocratic RP-HPLC separation of all four stereoisomers (SR,RS,SSandRR) of labetalol, chemically known as 2-hydroxy-5-[1-hydroxy-2-((1-methyl-3-phenylpropyl) amino)ethyl] benzamide, an antihypertensive agent with combined alpha- and beta-adrenoceptor blocking activities, have been presented. In the developed RP-HPLC system the conventional octadecylsilica packed column and double-helical chelate (-)(M)(λ,Λ)-[4,4'-(1S)-methyl-(2R)-propylethane-diyldi-imino) bis(pent-3-en-2-onato)]nickel(II) as the chiral mobile phase additive was used.

ISSN:1082-6076    

DOI:10.1081/JLC-100101725

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A free solution capillary electrophoresis method was developed to separate and quantitate codeine (CD), caffeine (CF), butalbital (BB), and aspirin (AP) in a mixture. The mixture was injected hydrodynamically for 5s at the anodic end and separation was performed on a fused silica capillary (72 cm × 50 μm i.d; 50cm to detector) at an applied voltage of 20 kV with 0.05 M phosphate run buffer pH 8. Separation was performed at ambient temperature and the total run time for analysis was 14 min. Detection was set at 220 nm. Calibration curves were prepared for CD, CF, BB, and AP with methyl p-hydroxy benzoate as internal standard. For each analyte, the correlation coefficients was greater than 0.999 (n=4). The RSDs % of ten replicate injections for each analyte were less than 1.4 %. The method was applied to the quantitation of CF, BB, and AP in a commercial tablet. Recoveries of the drug components were in the 96–104 % range.

ISSN:1082-6076    

DOI:10.1081/JLC-100101726

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Retinyl acetate in soy based infant formula was extracted by matrix solid phase dispersion (MSPD) and chromatographed by isocratic normal phase chromatography on a Si 60 column with a mobile phase of 0.28% (v/v) isopropanol in hexane. Detection was by fluorescence (Ex λ=325, Em λ=470). Fluorescence response was linear (r2=0.999) from 0.10 – 2.5 μg/mL. Recoveries determined on a soy based infant formula zero control reference material (ZRM) containing added analyte at five levels averaged 94.7% (n=25) with CV's from 0.57–3.53%. The method expands the use of MSPD extraction to the analysis of retinylacetate in soy based infant formulas.

ISSN:1082-6076    

DOI:10.1081/JLC-100101727

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The separation behavior of red blood cells (RBCs) in sedimentation field-flow fractionation (SdFFF) was investigated under higher field and flow conditions than used previously. This work shows that SdFFF separation of RBCs is fast with the total operating time less than 5 minutes. The resolution is high and the cells retain their integrity after separation. The optimization of cell separation by SdFFF was investigated.

ISSN:1082-6076    

DOI:10.1081/JLC-100101728

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A direct injection high-performance liquid chromatographic method is developed for the determination of cholesterol in egg-yolk. The described method involved an on-line sample clean-up procedure using column-switching technique and protein-coated RP-18 precolumn. The egg-yolk was diluted with tris buffer, pH 8.5 to produce homogenous sample and render it suitable for injection. On the precolumn, cholesterol was preseparated from endogenous components of the egg-yolk with tris buffer, pH 8.5 for 4 minutes. To complete the precolumn washing cycle, the solvent selector is automatically changed from tris buffer to 0.05 M phosphate buffer, pH 4.8 for 2 min, followed by 15% methanol in 0.05 M phosphate buffer, pH 4.8 for 1 min further.

ISSN:1082-6076    

DOI:10.1081/JLC-100101729

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor