Determination of organic acids in chinese herbal medicine by capillary zone electrophoresis

A capillary zone electrophoresis method was developed for the determination of chlorogenic acid,caffeic acid and ferulic acid in some Chinese herbal medicines.The influence of the pH and concentration of the running buffer,separation voltage and injection time on separation were examined.The best separation was achieved on a fused-silica capillary column(50 cm×75 μm I.D.) in a running buffer of 150 mmol/L boric acid(pH=8.7) with injection time of 8 s at 0.5 psi and an applied voltage of 23 kV at 25℃.The detection was performed with diode array detection at 320 nm.The calibration curve was linear over a range of 0.01～0.2 mg/mL for ferulic acid,chlorogenic acid and caffeic acid,with a correlation coefficients of 0.999,0.997 and 0.999,respectively.The detection limits(S/N=3∶1) for ferulic acid,chlorogenic acid and caffeic acid were 0.2 μg/mL,0.4 μg/mL and 0.2 μg/mL,respectively.The CZE method has been successfully applied to the analysis of organic acid in honeysuckle,taraxacum and propolis.