Effect of drying on the degradation of cationic surfactants and separationperformance in capillary zone electrophoresis of inorganic anions

Tetradecyltrimethylammonium bromide (TTAB) is used in capillary zone electr ophoresis (CZE) to control the direction and magnitude of the electroosmoti c flow and the migration time of analyte anions. Drying of the hygroscopic TTAB at 100 degrees C overnight has been found to influence the final CZE s eparation by providing improved resolution, precision of migration times, a nd enhanced detection response for hydrogenphosphate. Chemical analysis of the dried TTAB using IR and GC-MS indicated the presence of small amounts o f an unexpected tertiary alkylamine, tetradecyldimethylamine. This amine ap pears to contribute to the improved separation, probably by making more eff ective the masking of silanophilic activity at the capillary surface and/or generating a more stable double-layer. (C) 1999 Published by Elsevier Scie nce B.V. All rights reserved.