Thiamine analysis in biological media by capillary zone electrophoresis with a high-sensitivity cell

A capillary zone electrophoresis method with high-sensitivity cell (Z-cell) has been developed for the determination of thiamine in biological media ( plasma, urine, saliva). The urine samples were diluted (1:1, v/v) in water and were directly injected into the apparatus. For the quantitative assay o f thiamine in plasma it is necessary to precipitate the protein component. Good results were achieved by treating the sample with acetonitrile (1:3, v /v). Using a capillary with high sensitivity cell led to an approximately n ine-fold improvement of the detection limit compared to standard capillarie s and four-fold improvement compared to capillary with bubble cell. The sam ples in the biological media were analysed using a calibration curve for th iamine concentrations between 0.1 and 200 mu g ml(-1). The detection limit, the effective mobility and the relative standard deviation of the migratio n times and of the peak areas were determined. (C) 2000 Elsevier Science B. V. All rights reserved.