[Quantitative determinations of glycyrrhizic acid, glycyrrhetinic acid, morphine and sodium benzoate in compound liquorice tablets by capillary zone electrophoresis].

Capillary zone electrophoresis (CZE) was used to quantitatively determine the contents of glycyrrhizic acid, glycyrrhetinic acid, morphine and sodium benzoate in compound liquorice tablets. The detection wavelength was 228 nm and the applied voltage was 14 kV. Borax solution of 50 mmol/L was used as the background electrolyte and hydrochlorothiazide as the internal standard. There were all good linear relationships between the concentrations and the relative areas of glycyrrhizic acid, glycyrrhetinic acid, morphine and sodium benzoate. Their average recoveries were 98.2%, 97.3%, 97.1% and 97.5%, respectively. The method is simple, rapid and accurate.