Determination of micelle/water partition coefficients of cosmetic preservatives - Optimisation of the capillary electrophoretic method

The hydrophobicity of a group of molecules used as preservatives for aqueou s cosmetics, containing surfactants in the form of micelles, was evaluated by means of micellar electrokinetic capillary chromatography (MECC). Five d ifferent preservatives mixtures were examined, with a composition analogous to that employed in the preservation of cosmetic formulations. Sodium dode cyl sulphate and sodium dodecyl(polyoxyethylene)(1-4) sulphate were used as model surfactant and surfactant present in real cosmetic samples, respecti vely. The appropriate choice of the micellar velocity marker turned out to be a crucial point for the application of the MECC approach. (C) 2000 Elsev ier Science B.V. All rights reserved.