Developing a Procedure for the Selective Determination of Vitamin E on Human Skin Surface in Applying Oil Preparations

A straightforward procedure is developed for the selective determination of alpha-tocopherol acetate (vitamin E) in oil-based cosmetic products, focusing on the evaluation of the sorptive capacity of human skin and the uniformity of the distribution of the preparation on its surface. The procedure is designed to determine vitamin E after application as an oil solution, relying solely on the analyte’s absorption without additional reagents, such as ascorbic acid or an alkali. The procedure involves vitamin E extraction with isopropanol and measuring an analytical signal by UV spectrophotometry. The calibration curve exhibits linearity within the range 0.02–0.1 mg of vitamin E/mL. The limit of detection for vitamin E, calculated from the calibration curve equation and its slope, is 0.5 µg/mL. This procedure has demonstrated reproducibility, selectivity, rapidity, and simplicity.