Determination of retinol, retinyl palmitate, and retinoic acid in consumer cosmetic products

Abstract

Retinol and retinyl palmitate are frequently used in cosmetic products. A simple, rapid, and sensitive reversed-phase high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed for the quantitation of retinol, retinyl palmitate, and retinoic acid in cosmetic preparations. The analytes were extracted from a cosmetic/Celite mixture using a solvent system composed of equal amounts of hexane, isopropanol, and ethyl acetate, and the extract was injected directly into an HPLC chromatograph with a C18 column and UV detector set at 330 nm. Chromatographic separation was achieved by gradient elution with a mobile phase, starting with aqueous ammonium acetate buffer/methanol that was gradually changed to methanol/dichloromethane. The average recoveries of retinol, retinyl palmitate, and retinoic acid from spiked cosmetic products were 95% or higher. In a survey of twenty-nine consumer cosmetic skin care products labeled to contain retinoids, most products were found to contain either retinol or retinyl palmitate at concentrations up to 2.2% (w/w), while a few products contained both ingredients. A number of products also contained cis isomers of retinol that could be quantitatively distinguished from the all-trans compound. The method can be used to quantitate several retinoids and their isomers in cosmetic products. The method will be useful for obtaining information needed to estimate levels of exposure to retinoids from cosmetic products.