Simultaneous Determination of Glycyrrhizic Acid and Liquiritin in Glycyrrhiza uralensis Extract by HPLC with ELSD Detection

Simultaneous quantitative determination of glycyrrhizic acid and liquiritin in Glycyrrhiza uralensis extract was developed using a high performance liquid chromatography (HPLC) coupled to an evaporative light scattering detector (ELSD). A Luna C-18 column was used, along with a mobile phase consisting of acetonitrile and 3.0% (v/v) aqueous acetic acid in a gradient elution mode, at a flow rate of 1.0 mL/min. Parameters of ELSD were 105 degrees C for the drift tube temperature and 2.8 L/min for the gas flow-rate. Retention times of liquiritin and glycyrrhizic acid were 4.1 and 8.3 min, respectively. Logarithmic calibration curves were obtained for glycyrrhizic acid from 0.50 to 5.72 mu g (r(2)> 0.999) with a precision of 0.95% R.S.D and for liquiritin from 0.30 to 6.00 mu g (r(2)> 0.999) with a precision of 0.59% R.S.D. The limit of quantitation (LOQ) of glycyrrhizic acid and liquiritin were 168.3 ng and 200 ng (S/N=3), respectively. This method was successfully applied to quality evaluation in licorice raw materials and related commercial formulations.