Determination of sulfonylurea herbicides in water using solid-phase extraction followed by liquid chromatography with electrospray ion trap mass spectrometry

A method has been developed for confirmation and quantitation of ten sulfonylurea herbicides (nicosufuron, thifensulfuron-methyl, metsulfuron-methyl, sulfometuron-methyl, chlorsulfuron, ethametsulfuron-methyl, tribenuron, bensulfuron-methyl, pyrazosulfuron-ethyl and chlorimuron-ethyl) in water samples. Herbicides were extracted from water by off-line solid-phase extraction (SPE). Different types of absorbents were evaluated: silica-based ODS-C₁₈ and two polymeric sorbents, Cleanert HXN and Oasis HLB. Analyte determination and quantitation was performed by liquid chromatography with electrospray mass spectrometry (LC-ESI-MS) instrumentation, equipped with ion trap mass filter. Confirmatory analysis was carried out by LC/MS/MS. MS data acquisition was performed by a single or two-ion extracted ion monitoring program. The ten herbicides were measured in fortified tap water. Average recoveries of the nine analytes (except for tribenuron) from water samples were in the range of 77–109%, and the RSD ranged from 0.3 to 14.5%. The limit of detections (LODs) varied from 6 to 34.8 ng/L.