Analysis of hydroquinone and some of its ethers by using capillary electrochromatography.

Capillary electrochromatography (CEC) was used for the analysis of relevant compounds in cosmetic preparation. Hydroquinone (HQ) and some of its ethers (methyl-, dimethyl-, benzyl-, phenyl-, propyl-HQ derivatives) were analyzed by using an octadecylsilica (ODS) stationary phase packed in fused-silica capillary (100 microm I.D.; 30 cm and 21.5 cm total and effective lengths, respectively). 20 mM Ammonium acetate pH 6-acetonitrile (50-70%) were the mobile phases used for the experiments. The acetonitrile (ACN) content strongly influenced the resolution of the studied compounds as well as the efficiency and the retention factor. Baseline resolution for the studied analytes was achieved at both the lowest and the highest percentage of ACN, the last one providing the shortest analysis time. Mobile phase containing 70% of ACN was therefore used for the analysis of an extract of skin-toning cream declared to contain HQ. Good repeatability of both retention times, peak areas and peak areas ratio (Asample/Ainternational standard) was found. The calibration graphs were linear in the concentration range studied (5-90 microg/ml) with correlation coefficients between 0.9975 and 09991. The analysis of the cosmetic preparation revealed the presence of HQ (1.72%, w/w) and of two additional peaks (not identified).

Capillary zone electrophoresis in pharmaceutical analysis.

The paper presents a brief characterization of capillary zone electrophoresis, a modern analytical separation method with high expediency for practical applications, especially in pharmaceutical analysis. Basic theoretical considerations are presented and discussed to explain the effects of the operational parameters upon the separation efficiency and resolution of species. Descriptions of simple instrumentation and of the analytical procedure itself are given. Experimental examples are given of the separation of mixtures of pharmaceutically important compounds and of the effects of operational parameters, especially pH of BGE and voltage applied. Lastly, the practical application of CZE for analysis of isoxsuprine in commercial preparations is shown.

Capillary zone electrophoresis and mass spectrometry for the characterization of genetic variants of human hemoglobin.

This paper describes a simple and rapid analytical method for the structural identification of abnormal human hemoglobins. Globin chains obtained by precipitation of erythrocyte hemolysate in cold acetone are directly analyzed by capillary zone electrophoresis in coated capillaries without any prior treatment. The speed and the high resolving power of capillary zone electrophoresis allow fast differentiation of hemoglobins with similar charges. Capillary zone electrophoretic tryptic mapping has also been performed for each globin, so that complete variant characterization can be achieved by direct comparison of the variant tryptic map with the corresponding normal one. Coupling electrophoretic data with analysis of enzymatic digests by mass spectrometry according to the "fast atom bombardment mapping" procedure makes it possible to quickly identify amino acid variations. This paper describes how the method can be applied to the characterization of common and uncommon variants and underlines the advantages and limitations of the procedure along with its potential uses in structural analysis of proteins.

Chromatographic and cytogenetic analysis of in vivo metabolites of fluoranthene.

Fluoranthene metabolites in rat serum were analysed by high-performance liquid chromatography (HPLC) with UV and fluorescence detection and compared with in vitro metabolites obtained by incubation with microsomal fraction of rat hepatocytes. In order to resolve very polar fluorescent compounds present in rat serum, a modification of HPLC existing methods for in vitro metabolites separation was necessary. Mutagenic 2,3-dihydrodiol was identified in both in vitro sample and rat serum: this result is in good accord with cytogenetic analysis on rats bone marrow cells, that shows a slight but significant increase of sister chromatide exchanges.