CE-ED separation and determination of seasonal content variations of some active ingredients in toona sinensis (A. Juss) roem leaves

A method based on capillary zone electrophoresis with electrochemical detection (CE-ED) has been employed for the separation and determination of epicatechin, scopoletin, quercetin and gallic acid in Toona sinensis (A. Juss) Roem leaves. Seasonal variations of these ingredients in T. sinensis (A. Juss) Roem leaves collected in April, June and August, were discussed. Several important factors including running buffer acidity, separation voltage, working electrode potential and etc., were evaluated to acquire optimum analysis conditions. Under the selected optimum conditions, these analytes could be well separated. Good linear relationship was established between the peak current and the concentration of each analyte over 2–3 orders of magnitude with detection limits (S/N = 3) ranging from 4.00 × 10−8 to 1.73 × 10−7g mL−1. The proposed method has been successfully applied for the evaluation of the seasonal content variation of these four active ingredients in T. sinensis (A. Juss) Roem leaves with satisfactory results.