[Determination of bioactive components in Semencustae by capillary electrophoresis with electrochemical detection]

A method of high performance capillary electrophoresis with electrochemical detection (CE-ECD) has been developed for the determination of five bioactive components in Semencustae, namely rutin, hyperoside, kaempferol, p-coumaric acid and quercetin. The effects of several factors such as the acidity and concentration of the running buffer, the separation voltage, the applied potential and the injection time on CE-ECD were investigated. Under the optimized conditions, these five components can be separated in a 50.0 mmol/L borax running buffer (pH 9.0) within 19 minutes. A 300 microm diameter carbon disk electrode was used as the working electrode positioned carefully opposite to the outlet of the capillary in a wall-jet configuration at potential of + 950 mV (vs. saturated calomel electrode as reference electrode, SCE). Good linear relationships were established between the peak current and concentration of analytes over two orders of magnitude. The detection limits (S/N = 3) were 1.93 x 10(-5), 3.55 x 10(-4), 3.65 x 10(-5), 1. 73 x 10(-5) and 1.46 x 10(-4) g/L for rutin, hyperoside, kaempferol, p-coumaric acid and quercetin, respectively. The method has been successfully applied to the determination of these analytes in Semencustae samples after a relatively simple extraction procedure, and the assay results were satisfactory.