Determination of active ingredients of Ilex Purpurea Hassk and its medicinal preparations by capillary electrophoresis with electrochemical detection

A method based on capillary electrophoresis with electrochemical detection has been developed for the separation and determination of isovanillic acid, gentisic acid, kaempferol, quercetin, caffeic acid and protocatechuic acid in Ilex Purpurea Hassk and its medicinal preparations for the first time. The effects of working electrode potential, pH and concentration of running buffer, separation voltage and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be separated in a 50 mmol l−1 borate buffer (pH 9.0) within 21 min. A 300 μm diameter carbon disk electrode has a good response at +0.95 V (versus SCE) for all analytes. The response was linear over three orders of magnitude with detection limits (S/N = 3) ranging from 3 × 10−8 to 2 × 10−7 g ml−1 for the analytes. The method has been successfully applied to the analysis of real sample, with satisfactory results.