Combination of aqueous and non-aqueous capillary electrophoresis with electrospray mass spectrometry for the determination of drug residues in water

The work presented in this paper deals with the combination of capillary electrophoresis (CE) with electrospray mass spectrometry (MS) for the determination of drug residues in water. CE/MS methods have been developed based on either aqueous or non-aqueous ammonium acetate solutions as the carrier electrolyte for the separation of selected drugs. The different separation conditions were compared in terms of selectivity and detection limits; both aqueous and non-aqueous CE proved to be suitable for the present analytical task, exhibiting detection limits between 3 and 93 mug/dm(3) (injected standard concentration) corresponding to concentrations between 5 and 19 ng/dm(3) in the sample. A combination of liquid-liquid extraction and solid-phase extraction was investigated for sample pretreatment, yielding enrichment factors of 10000. The applicability of CE/MS was demonstrated for the analysis of several river water samples.