Micellar Electrokinetic Capillary Chromatography with Cationic Surfactants

Abstract

Abstract A series of alkyltrimethylammonium chloride and bromide surfactants were evaluated in micellar electrokinetic capillary chromatography (MECC) of urea herbicides, alkylbenzenes and phenylalkylalcohols. The magnitude of the anodal electroosmotic flow obtained with these cationic micellar phases was largely unaffected by the length of the alkyl chain of the surfactant while the migration time of the micelle increased with decreasing the length of the alkyl tail. The net result was an increase in the retention window as the size of the alkyl tail of the surfactant decreased. The breadth of the retention window stayed almost the same when the micelle counterions were changed from chloride to bromide. At constant micellized surfactant concentration, the capacity factors of neutral solutes increased linearly with increasing alkyl chain length of the surfactant, indicating an increase in the hydrophobic phase ratio of the MECC systems. Under this condition, the value of the methylene group selectivity fo...