Analytical Method for the Identification and Assay of Kojic Acid, Methylparaben, and Propylparaben in Cosmetic Products Using UPLC: Application of ISO 12787:2011 Standard.

A straightforward, fast UPLC method is developed for the identification and quantification of kojic acid (KA), methylparaben (MP), and propylparaben (PP) in 15 cosmetic products (skin whitening creams and lotions). Chromatographic separations for KA, MP, and PP were obtained in 3.5 min on an Acquity BEH-C18 column (100 × 2.1 mm, 1.7 μm particle size) as the stationary phase at 260 nm (diode-array detector), with the mobile phase comprising a mixture of 0.01 M dibasic potassium phosphate and methanol-acetonitrile (50 + 50). Validation studies were performed according to in-house established criteria. There was a linear function of concentrations over the range of 0.4-1.6 μg/mL for KA, MP, and PP. The LOQ for all components was 0.2 μg/mL using the S/N method. Good separation of analytes was observed, with acceptable values of resolution and tailing. The analytical approach defined in the ISO 12787:2011 standard ("Cosmetics-Analytical methods-Validation criteria for analytical results using chromatographic techniques") was used for the assay of cosmetic samples.