Determination of active ingredients in mutouhui by capillary electrophoresis with electrochemical detection

Capillary zone electrophoresis with electrochemical detection has been used for the separation and determination of scopoletin, hyperin, chlorogenic acid, and quercetin in Mutouhui. The effects of several important factors, including running buffer acidity, separation voltage, and working potential, were evaluated to achieve the optimum conditions. The working electrode was a 300-microm carbon disk electrode at a working potential of + 0.95 V (versus saturated calomel electrode). Under the optimum conditions, the analytes can be well separated within 20 min in a 75-cm-long fused-silica capillary. The current response was linear over two orders of magnitude with detection limits (S/N = 3) ranging from 2.70 x 10(-8) g/mL to 1.30 x 10(-7) g/mL for all analytes. This method was used successfully in the analysis of Mutouhui, and the assay results were satisfactory.