A new method for the simultaneous oxidation and reduction determination of nitrendipine is presented based on the micellar electrokinetic chromatography (MEKC) separation of the analytes coupled to a dual-channel electrochemical detection system. In this system, single working electrode (carbon paste microelectrode) was employed. Two amperometric detectors were placed in parallel and detection potentials were set at ＋0.7 V and－0.8 V vs. SEC, respectively. Nitrendipine was determined with oxidation and reduction at the same time, and the signals of oxidation and reduction were collected and processed by the software of the system in real time. In this study, efficient, rapid and versatile electrophoretic conditions were obtained which were 8 mmol/L ammonium chloride with pH9.0 adjusted with 25% ammonia, and 6 mmol/L sodium dodecyl sulfate (SDS) in water-methnol (90:10, V:V). The effects of the working electrode, detection potential, concentration of sodium dodecyl sulfate, methanol, electrolyte, applied voltage and injection time on the determining are discussed. The method was applied to nitrendipine tablet and satisfactory results were obtained.

Key words: MICELLE, ELECTROKINETICS, CAPILLARY CHROMATOGRAPHY, CHANNELS, ELECTROCHEMISTRY, DETECTION, CARDIOVASCULAR DISEASES, DRUGS ANALYSIS, ELECTROPHORESIS