Analysis of surfactants by capillary electrophoresis mass spectrometry

Capillary electrophoresis/mass spectrometry (CE/MS) was applied to an analysis of surfactants. The detection limit of sodium dodecyl sulfate (SDS) was determined. Compared to indirect UV detection, SDS was detected with higher sensitivity by MS detection. The detection limit at a signal-to-noise ratio of 2 was 0.05 mu g/ml when an untreated fused-silica capillary was used. Sodium decyl sulfate and sodium tetradecyl sulfate were detected by CE/MS as impurities in SDS. CE/MS easily showed a difference in purities of commercial SDS among three different suppliers. Composition analyses of commercial surfactants (sodium polyoxyethylene(2) dodecyl ether sulfate and dodecyl dimethylaminoacetic acid betaine) were also performed by CE/MS. A number of components and impurities were identified according to each molecular mass. It has been shown that CE/MS is a promising analytical tool for the analysis of surfactants.