Electrically driven microseparation methods for pesticides and metabolites: III. Capillary electrochromatography with novel silica-based stationary phases having a surface-bound surfactant moiety

A silica-based stationary phase with surface bound silylpropyl trialkylammo nium functions was introduced and evaluated in the capillary electrochromat ography of alkylbenzenes and pesticides. This stationary phase is referred to as octadecyldimethyl(3-trimethoxysilylpropyl) ammonium-silica (ODAS) and has quaternary amine functions that generate an anodic electroosmotic flow (EOF) and octadecyl functions that are responsible for solute retention by a reversed-phase chromatography mechanism. The ODAS stationary phase was c haracterized over a wide range of elution conditions in term of EOF and ret ention behavior of alkylbenzene homologous series. The ODAS stationary phas e proved useful in the separation of pesticides as well as in the on-column preconcentration of dilute pesticide samples, thus permitting the detectio n of solution at 7 x 10(-7) M using a UV detector.