Determination of thioglycolic acid in cosmetics by reversed-phase high performance liquid chromatography

A reversed-phase high performance liquid chromatographic method was developed for the determination of thioglycolic acid(TGA) in cosmetics.Chromatography separation was carried out on a Kromasil C18 column.Mobile phase for isocratic elution was a blend solution consists of acetonitrile and 0.01 mol/L potassium dihydrogen phosphate solution(pH adjusted to 2.5 by phosphoric acid) with volume ratio of 10∶ 90,and flow rate of 1.0 mL/min.Detection was carried out at 215 nm with column temperature maintained at 30 ℃.The sample injected was 20 μL.Results showed that under those conditions,when the mass concentration of thioglycolic acid ranges within 5.0~150.0 μg/mL,it indicates good linear relationship against the peak area.The linearity regression equation can be expressed as Y=5 100X-13 400(r=0.999 8).The average recoveries achieve ranging from 98.4% to 100.8% with relative standard deviations of 0.09%~0.84%.