title: Determination of thioglycolic acid in cosmetics by capillary electrophoresis.
abstract: 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.
authors.affiliation: Beijing Key Laboratory of Diagnostic and Traceability Technologies for Food Poisoning, Beijing Center for Disease Control and Prevention, Beijing 100013, China; College of Science, Agricultural University of Hebei, Baoding 071001, China.
authors.forename: Na
authors.initials: N
authors.lastname: Xie
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Ding
authors.forename: Xinyu
authors.initials: X
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Shan
authors.initials: S
authors.lastname: Zhao
authors.forename: Zhi
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000042:Absorption; D002021:Buffers; D002138:Calibration; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003358:Cosmetics / Q000737:chemistry*; D019075:Electrophoresis, Capillary; D006203:Hair Preparations / Q000737:chemistry*; D006204:Hair Removal; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D057230:Limit of Detection; D010710:Phosphates / Q000737:chemistry; D015203:Reproducibility of Results; D012822:Silicon Dioxide / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013864:Thioglycolates / Q000032:analysis* / Q000737:chemistry*
chemical_list: D002021:Buffers; D002593:Cetrimonium Compounds; D003358:Cosmetics; D006203:Hair Preparations; D010710:Phosphates; D012997:Solvents; D013864:Thioglycolates; D012822:Silicon Dioxide; C017487:2-mercaptoacetate; C018279:sodium phosphate; D000077286:Cetrimonium
keywords: Capillary electrophoresis; Cosmetics; Depilatory creams; Hair-treatment products; Thioglycolic acid