Enantioseparation of Malathion, Cruformate, and Fensulfothion Organophosphorus Pesticides by Mixed-Mode Electrokinetic Capillary Chromatography

Mixed-mode electrokinetic capillary chromatography (mixed-mode ECC) has been used for the enantioseparation of organophosphorus pesticides. In mixed-ECC, a combination of three pseudostationary phases including surfactants, neutral, and charged cyclodextrins, are used to resolve very challenging enantioseparation problems. The conditions mimic a mixture of micellar electrokinetic capillary chromatography (MECC) and dual-cyclodextrin electrokinetic capillary chromatography (dual-CECC) conditions. In this work SDS, carboxymethyl- g -CD, hydroxypropyl-BCD, and organic modifiers were mixed at various concentrations in order to achieve enantioseparation of three organophosphorus pesticides - cruformate (ruelene), malathion, and fensulfothion. The best condition for separation of ruelene enantiomers was by using a mixture of 70 mM SDS/15 mM carboxymethyl-BCD/45 mM hydroxypropyl-BCD/20% (v/v) acetonitrile in 20 mM borate buffer at pH 8.6, with applied voltage of 25 kV at 25°C. Malathion enantiomers were successf...