DETERMINATION OF GLYCOLIC ACID IN COSMETIC PRODUCTS BY SOLID-PHASE EXTRACTION AND REVERSED-PHASE ION-PAIR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A procedure has been developed for the assay of glycolic acid in cosme tic products by reversed-phase high-performance liquid chromatography using an ion-pairing method. After dissolution in tetrahydrofuran-wate r (90:10, v/v), samples were purified by solid-phase extraction using silica-based strong anion-exchange cartridges and analysed directly on an Ultrasphere ODS column with UV detection at 210 nm and methanol-ph osphate buffer (2:98, v/v), containing tetrabutylammonium iodide, as t he mobile phase. Recovery of glycolic acid from different cosmetic mat rices was between 92.4 and 96.2% and the precision of the method was b etter than 5.4% relative standard deviation. The procedure is rapid, s imple, selective and it is suitable for routine analyses of commercial cosmetics. (C) 1998 Elsevier Science B.V.