Analysis of cationic surfactants by capillary electrophoresis

Capillary zone electrophoresis was applied to the analysis of N-benzyl-N-alkyl-N,N-dimethylammonium chloride compounds with different alkyl chain lengths (C-12-C-18) by direct UV detection. A tetrahydrofuran-containing buffer was used to prevent the occurrence of micellization and adsorption of the surfactants, thereby yielding adequate separations according to their free-form electrophoretic mobilities. Resolution, theoretical plate number, reproducibility and precision were ascertained. Finally, the electrophoretic method was applied to the qualitative and quantitative determination of an industrial mixture of C-n-benzyl surfactants.