Polarographic determination of sunscreen agents in cosmetic products in micellar media.

This paper introduces a simple, fast and reliable electroanalytical method for differential-pulse polarography based on electrochemical reduction at a dropping mercury electrode. The method was validated for the determination of 2-ethylhexyl-4-methoxycinnamate (EHMC) alone and in association with 4-methylbenzylidene camphor (MBC) or 2-hydroxy-4-methoxybenzophenone (BENZ-3) in samples of commercial cosmetic preparations. The supporting electrolyte that provided the best-defined and most intense peak current for EHMC determination was Britton-Robinson buffer (pH 4.0) in the presence of a cationic surfactant. Under optimized conditions, EHMC exhibited one single peak of reduction at -1.49 V versus Ag/AgCl. A limit of detection of 3.76 x 10(-8)mol L(-1) and a limit of quantitation of 1.25 x 10(-7) mol L(-1) were found for the pure EHMC standard. A good average recovery rate was reached for all the samples analyzed.