Determination of triorganotin species in water samples by liquid chromatography–electrospray-mass spectrometry

Liquid chromatography coupled to electrospray–mass spectrometry (LC–ES-MS) with positive ion detection was evaluated for the determination of tributyltin and triphenyltin in water samples using tripropyltin as internal standard. The separation was performed in the isocratic mode on a silica-based C18 column with a mobile phase containing 0.02% trifluoroacetic acid in acetonitrile–water (50:50, v/v). The optimum LC–ES-MS conditions were established and quantification was performed on the basis of the [M]+ ions. Limits of detection for standard solutions were 100 and 200 pg Sn injected for triphenyltin and tributyltin, respectively, and good reproducibility was observed. Solid-phase extraction was carried out on C18 cartridges to preconcentrate the analytes from natural water samples, with recoveries ranging from 80 to 110%. Limits of detection for SPE–LC–ES-MS were in the range of low ng l−1, which demonstrates the suitability of the method for environmental samples.