Determination of active ingredients of Apocynum Venetum by capillary electrophoresis with electrochemical detection

A simple, reliable and reproducible method, based on capillary electrophoresis (CE) with electrochemical detection (ED), for the determination of three active ingredients of both Apocynum Venetum compound tablets and medicinal herbs was described. The active ingredients mainly consist of rutin, d-catechin and quercetin. Operated in a wall jet configuration, a 300 mum diameter carbon-disk electrode was used as the working electrode, which exhibits good responses at +950 mV (vs. SCE) for the three analytes. Under the optimum conditions, the analytes were base-line separated within 19 min, and excellent linearity was obtained in the concentration range from 1.0 x 10(-4) g/ml to 1.0 x 10(-6) g/ml. The detection limit (S/N = 3) was 3.0 x 10(-7) g/ml, 5.0 x 10(-7) g/ml, and 4.0 x 10(-7) g/ml, for d-catechin, rutin and quercetin, respectively. This work provides a useful method for the analysis of traditional Chinese medicines.