Optimization and Validation of a Fast UPLC Method for Simultaneous Determination of Hydroquinone, Kojic Acid,...

A previously published HPLC method for the simultaneous determination of six major components (hydroquinone, kojic acid, octinoxate, avobenzone, butylated hydroxyanisole, and butylated hydroxytoluene) in a skin-whitening cream was transferred and optimized to an ultra-performance LC system. Separation was achieved in a ZORBAX SB-Phenyl Rapid-Resolution High Throughput column (2.1 × 100 mm, 1.8 μm), using a mobile phase consisting of water with 0.1% acetic acid and acetonitrile at a flow rate of 0.7 mL/min. The column was maintained at 40°C, and detection was carried out at 230 nm using a diode-array detector. These chromatographic conditions allow the separation of the six compounds in 3 min instead of 14 min. The extraction procedure was optimized, reducing the time and demonstrating its suitability. The method was validated according to International Conference on Harmonization guidelines, with respect to specificity, precision, accuracy, and linearity. Selectivity was found to be satisfactory. Linear regression analysis data for all compounds showed a good linear relationship, with r2 > 0.999 in the concentration range of 50-120% of the label claim for each compound. The RSD for precision and accuracy of the method was found to be less than 2% for all compounds. Comparison of system performance with the previously published HPLC method was made with respect to analysis time, efficacy, and resolution. The proposed method is faster and consumes less solvent and was applied in the determination of six major compounds in batches of skin-whitening cream manufactured during the validation process.