SIMULTANEOUS DETERMINATION OF GLYCYRRHIZIC ACID AND GLYCYRRHETINIC ACID IN COSMETICS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A method for the simultaneous determination of glycyrrhizic acid (G) and glycyrrhetinic acid (GA) in cosmetics by means of high performance liquid chromatography (HPLC) is described. Samples (cosmetics) were extracted with tetrahydrofuran or tetrahydrofuran containing 5-10% water. The extracts were passed through Bondelute NH2 cartridge (3 ml). After washing the cartridge with tetrahydrofuran and methanol, G and GA were eluted with a mixture of 0.2 M KH2PO4-acetonitrile (1:1). G and GA were separated and determined by HPLC on an ODS column (TSKgel-ODS 80Th(M), 4.6 x 150 mm) using a mobilephase [CH3CN:H2O (65:35)] containing 0.2% (w/v) tri-n-octylamine, 0.4% (w/v) acetic acid, 0.1% (w/v) EDTA-2Na) Recoveries of G and GA from cosmetics (lotion, milky lotion, cream, hair tonic, etc.) were more than 95%.