Rapid direct determination of pesticides and metabolites in environmental water samples at sub-microg/l level by on-line solid-phase extraction-liquid chromatography-electrospray tandem mass spectrometry.

A very rapid, multi-residual, sensitive and specific procedure for determining 35 pesticides in environmental ground and surface water in proposed. It is based on the use of solid-phase extraction (SPE) combined on-line with liquid chromatography (LC) electrospray (ESI) tandem mass spectrometry (MS-MS). Simultaneous target analysis of 29 pesticides (1 fungicide, 16 insecticides, 10 herbicides and 2 acaricides) and 6 metabolites with positive or negative ionization was reached by the direct injection of only 1.3 ml of filtered water sample, with a total analysis time of 18 min. The SPE-LC-MS-MS method was validated, obtaining good results for all compounds at 0.5 and 0.1 microg/l. Most of them could be correctly quantified at a concentration level as low as 25 ng/l. Efficiency and applicability of this method was evaluated by the analysis of several samples included in a monitoring program.