Determination of Thioglycolic Acid and Dithiodiglycolic Acid in Cold Wave Lotions by High Performance Liquid Chromatography

Abstract

A rapid and simple method by high performance liquid chromatography (HPLC) was studied for the determination of thioglycolic acid (TGA) and dithiodiglycolic acid (DTDGA) in hair-waving solutions. A reverse phase ODS-silica was used as a column, and the eluent was 15% methanol adjusted to pH 2.0 with phosphoric acid. Chromatograms were monitered at UV 220 nm. DTDGA showed a single peak when the eluent pH was below 2.0. Sample solutions were prepared by a simple procedure, direct dilution with water. By using model samples containing 2, 5 and 7% of TGA, the proposed (HPLC) method was compared with iodometric determination. TGA data by HPLC method agreed with iodometric data, and the recoveries of DTDGA spiked to a model sample at the level of 0.5-3.0% were 102-106% by HPLC method, but 40-90% by iodometry.