[Determination of epinephrine, chlorpromazine and promethazine by capillary electrophoresis with scanning voltammetric detector].

With a self-constructed electrochemical detection system, the determination of epinephrine, chlorpromazine and promethazine has been studied by using capillary electrophoresis with scanning voltammetric detector. Scanning potential generation and data acquisition were carried out with D/A and A/D converter board that mounted on a 486DX66 computer. A complex software, which was written by authors in BORLAND C++, was serve to data acquisition, abstraction of three-dimension data, display and print of the electrophorograms. Using a 25 microns x 70 cm fused-silica capillary, the optimum conditions for separation and detection of titled drugs are 10 mmol/L K2HPO4 + H3PO4 (pH 3.0) running electrolyte, 20 kV separation voltage, hydrodynamic injection 10 s at 20 cm height, scanning potential from +0.4 to +1.0 V vs. SCE. With the optimizing condition, the separation of titled drugs is satisfactory, and good reproducibility and low limit are obtained. In this study, all experiments are carried out under air-conditioning (18 degrees C) and constant humidity (relative humidity 50%). In comparison to amperometric detection, scanning voltammetric detection has the advantages of minimizing fouling of the working electrode surface, and direct identification of unknown chemicals by voltammetric curves.