J. C. Hubinger, D. C. Havery, Office of Cosmetics and Colors, CFSAN, FDA, College Park, MD
Background: Retinol and retinyl palmitate are frequently used in cosmetic skin care products but may be irritating to the skin at higher concentrations.
Methods: A simple, rapid and sensitive reversed‑phase HPLC method with 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 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.
Results: The method was validated, and average recoveries of retinol, retinyl palmitate and retinoic acid were 95% or higher. In a survey of 29 consumer cosmetic skin care products, most products were found to contain either retinol or retinyl palmitate at concentrations up to 2.0%, while a few products contained both ingredients. Several cis isomers of retinol and retinoic acid were also isolated from cosmetic products with the method and could be quantitatively distinguished from the all-trans compounds.
Conclusions: The method can be used to accurately quantitate levels of several retinoids and their isomers in cosmetic products.