Determination of strychnine and brucine in traditional Chinese medicine preparations by capillary zone electrophoresis with micelle to solvent stacking

A novel micelle to solvent stacking on-line sample preconcentration technique in capillary zone electrophoresis (MSS-CZE) has been developed to determine the strychnine and brucine in traditional Chinese medicine preparations. The optimal running buffer was 30 mmol/L H3PO4 containing 20% acetonitrile at pH 4.0. The sample matrix was 8 mmol/L H3PO4 containing 5 mmol/L sodium dodecyl sulfate (SDS) at pH 3.0. The established MSS-CZE method afforded more than 50-fold improvements in concentration sensitivity compared with typical CZE-UV analysis. The calibration curve was linear in the range from 0.2 to 15.0 μg/mL for both strychnine and brucine, with correlation coefficients of 0.9984 and 0.9976, respectively. The limits of detection (S/N = 3:1) for strychnine and brucine were 0.02 and 0.05 μg/mL, respectively. The MSS-CZE method has been successfully applied to the analysis of strychnine and brucine in Chinese medicinal preparations.