HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ASSAY FOR COMMON SUNSCREENINGAGENTS IN COSMETIC PRODUCTS, BOVINE SERUM-ALBUMIN SOLUTION AND HUMAN PLASMA

This paper reports the development of a reversed-phase high-performanc e liquid chromatographic assay for quantifying five of the most common sunscreen agents, namely 2-ethylhexyl-p-dimethyl aminobenzoate (Escal ol 507), 2-ethylhexyl-p-methoxycinnamate (Parsol MCX); 4-tert.-butyl-4 '-methoxydibenzoylmethane (Parsol 1789), 2-hydroxy-4-methoxybenzopheno ne-3 (oxybenzone) and 2-ethylhexyl-salicylate (octylsalicylate). The a ssay permits analysis of the sunscreen agents in formulations and in b iological fluids, including bovine serum albumin (BSA) solution, a com mon additive to in vitro skin diffusion cell receptor fluids, as well as human plasma. Separation was achieved using an ODS C-18 column with a methanol-water (88:12) mobile phase. The analytes were detected by ultraviolet light absorption at a wavelength of 315 nm. The assay was linear with minimum detectable limits, calculated as greater than 3-ti mes the baseline noise level: for oxybenzone and Escalol 507, 0.05 mu g/ml; for Parsol 1789 and Parsol MCX, 0.1 mu g/ml; for octylsalicylate , 1 mu g/ml. Recoveries from both plasma and 2% BSA were within the ra nge 89-107%. The inter- and intra-day coefficients of variation for th e five agents were not more than 4% at the upper end of the linear ran ge and not more than 10% at the lower end. Preliminary stability studi es of the sunscreen agents in a commercial product and in two diffusio n cell receptor fluids were also conducted.