Colorimetric detection of thioglycolic acid based on the enhanced Fe3+ ions Fenton reaction

Based on Fenton reaction without adding nanomaterials, a simple colorimetric sensor for detecting thioglycolic acid (TGA) was developed. By reducing Fe3+ ions to Fe2+ ions, TGA efficiently stimulates Fenton reaction through accelerating Fe3+/Fe2+ redox cycle. Owing to this, the accelerated decomposition of H2O2 generates more OH radicals, which cause a significant blue change in the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB). Compared with Fe3+/H2O2/TMB system, this sensor can be operated over a wider pH range from 4.0 to 8.0. The calibration curve of TGA is achieved in the concentration range of 0.046-7.37 μg mL−1 under optimized conditions, and the detection limit of TGA is 0.036 μg mL−1 (S/N = 3). This sensor has been successfully applied to the detection of TGA in cold wave lotion with recovery rates between 99.1 and 101.6%, which has broad application prospects in cosmetic analysis and environmental monitoring.