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A sensitive method for the simultaneous determination of 30 sulfonylurea herbicides in tap and leaching waters has been developed. Liquid chromatography tandem-mass spectrometry (LC-MS2) in electrospray ionization positive mode was used for the separation, identification and quantification of these compounds. The procedure involves a preconcentration step based on solid-phase extraction with a silica-based bonded C-18 cartridge (Sep-Pak Plus) and a N-vinyl-pyrrolidone polymer cartridge (Oasis HLB). The best results were obtained with Oasis HLB using methanol as elution solvent. Average recoveries of 30 analytes from water samples were in the range of 79-115% with a relative standard deviation of <6.1%. The limits of quantification (LOQs) obtained in tap and leaching water samples were in the range of 0.1-5.9 and 0.4-5.8 ng L-1, respectively. The proposed method was used to determine sulfonylurea herbicide levels in leaching water samples taken from three lysimeters located in an experimental greenhouse. (C) 2012 Elsevier B.V. All rights reserved.