Determination of psoralen and isopsoralen in traditional Chinese medicines by capillary zone electrophoresis with amperometric detection

A simple, reliable and reproducible method was developed for determination of psoralen and isopsoralen in several traditional Chinese medicines, such as Shouwu Pian, Gubenkechuan Pian, was described in this paper. It was based on capillary zone electrophoresis with amperometric detection (CZE-AD). A carbon-disc electrode was used as working electrode. The optimal conditions of separation and detection were pH7.6 phosphate buffer (20 mM), 20 kV for the separation voltage and 1.00V (vs. Ag/AgCl) for the detection potential. The linear ranges were 6.90 × 10^-5∼ 1.30 × 10 ^-7 mol L^-1 for psoralen and 5.0 × 10 ^-5∼ 1.80 × 10^-7 mol·L^-1 for isopsoralen with the correlation coefficient of 0.9984 and 0.9994, respectively. The detection limits for psoralen and isopsoralen were 4.2 × 10 ^-8 mol·L^-1 and 6.0 × 10^-8 mol·L^-1 based on the signal to noise ratio of 3. The method built in this paper was directly applied to the determination of several traditional Chinese medicines with some simple pretreatment. The assay result was satisfactory.