Determination of thioglycolic acid in cosmetics by capillary electrophoresis

• Published in: Journal of pharmaceutical and biomedical analysis 2014-01, Vol.88, p.509-512
• Main Authors: Xie, Na, Ding, Xiaojing, Wang, Xinyu, Wang, Ping, Zhao, Shan, Wang, Zhi
• Format: Article
• Language: English
• Subjects: Absorption; Buffers; Calibration; Capillary electrophoresis; Cetrimonium Compounds - chemistry; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Cosmetics; Cosmetics - chemistry; Depilatory creams; Electrophoresis, Capillary; Hair Preparations - chemistry; Hair Removal; Hair-treatment products; Hydrogen-Ion Concentration; Kinetics; Limit of Detection; Phosphates - chemistry; Reproducibility of Results; Silicon Dioxide - chemistry; Solvents - chemistry; Thioglycolates - analysis; Thioglycolates - chemistry; Thioglycolic acid
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/j.jpba.2013.10.003

•TGA was well separated from matrix, which was beneficial for quantitation.•Sample solution could be directly injected after simple sample pretreatment.•High sample throughput without solvents is beneficial for routine analysis.•The results of HPLC, IC and CE demonstrated the accuracy of the CE method. A new and simple method for the accurate determination of thioglycolic acid (TGA) in cosmetics was developed using capillary electrophoresis (CE) with diode array detection at 236nm. The CE separation was performed on an uncoated fused silica capillary with a separation buffer solution containing 300mmolL−1 tri-sodium phosphate and 0.5mmolL−1 cetyltrimethylammonium bromide at a voltage of −5kV. Both the intra- and inter-day precisions of the method were 1.4%. The calibration curve between the corrected peak areas and the concentrations of the TGA was linear within the concentration range of 0.006–1.0mgmL−1 with a correlation coefficient (r) of 0.9998. The limit of detection and limit of quantitation were 0.002mgmL−1 (S/N=3) and 0.006mgmL−1 (S/N=10), respectively. The average recoveries at the spiked levels of 0.125, 0.250 and 0.500mgmL−1 were 96.9%, 102.3% and 94.0% with the relative standard derivations of 2.1%, 3.9% and 2.2%, respectively. The method was cross-validated by both high performance liquid chromatographic and ion chromatographic method. Eighty-five commercial depilatory creams and hair-treatment products were analyzed with satisfactory results.