Rapid and visual detection of benzoyl peroxide in cosmetics by a colorimetric method

In this work, a colorimetric method was developed to determine benzoyl peroxide (BPO) illegally added in cosmetics via naked eyes. Based on the reaction between 3,3',5,5'-tetramethylbenzidine and BPO, a blue-green-colored production was obtained and detected. Factors influencing the color reaction were examined. Sample pretreatments were systematically investigated to eliminate emulsion interference when extracting BPO from toner, gel, cream, lotion and cleanser. Under the optimized conditions, the linear range of detection was from 0.01 mmol/L to 0.5 mmol/L. The limit of detection was 9.1 mg/kg in real samples. This method can be utilized to detect BPO in different kinds of cosmetics, with recoveries between 77.2 and 121.5%. Illegally added BPO was detected in an anti-acne cleanser product by this method. A portable device was also exploited for direct and on-site BPO determination in cosmetics, requiring no sample preparation with absence of laboratory equipment. This proposed method can be successfully applied to determine the illegally addition of BPO in cosmetics.