A Stability Indicating RP-HPLC Method for Simultaneous Estimation of Ethylhexyl Triazone and Bemotrizinol in Sun Care Formulations

A novel stability indicating RP-HPLC method was developed for simultaneous estimation of Ethylhexyl triazone and Bemotrizinol in sun care formulations. Separation of Ethylhexyl triazone, Bemotrizinol and their degradation products was achieved on Waters symmetry C18 (150 × 3.9 mm, 5µ) as stationary phase and mixture of pH 4.50 ammonium formate buffer and 1,4-dioxane (20:80, v/v) as mobile phase. Both analytes were simultaneously measured at UV detection of 311 nm. Method was validated for specificity, method precision (Intra-day and inter-day), linearity, accuracy and robustness as per ICH guideline. Ethylhexyl triazone and Bemotrizinol were linear in the concentration range of 0.10-225 µg/mL and 0.12-225 µg/mL respectively with correlation coefficient of > 0.999. This method can be utilized in cosmetic industries to monitor both analytes in sun care formulations to assure the quality of the products.