ABSTRACT
Objective:To establish an HPLC method for the simultaneous determination of 18α-glycyrrhizic acid and 18β-glycyr-rhizic acid in diammonium glycyrrhizinate .Methods:A Diamonsil C18 column (200 mm ×4.6 mm, 5 μm) was used with the mobile phase of water (water-60%perchloric acid solution:48∶0.5, adjusting pH to 8.0 with ammonium hydroxide)-methanol (48∶52). The detection wavelength was set at 248 nm and the flow rate was 1.0 ml· min-1 .The column temperature was 30℃and the injection volume was 20 μl.Results:18α-Glycyrrhizic acid and 18β-glycyrrhizic acid were well separated .They had a good linear relationship within the range of 0.005 0-1.000 0 mg· ml-1(r=0.999 7 and 0.999 3).The average recovery was 99.7%and 99.1%, and RSD was 0.9%and 0.4%, respectively (n=9).Conclusion:The method is accurate, simple and reproducible, which can be used for the simultaneous determination of the two constituents in diammonium glycyrrhizinate .