High performance liquid chromatography-tandem mass spectrometry method for quantifying phenylurea herbicides and their main metabolites in amended and unamended soils.

A sensitive multiresidue method for the simultaneous determination of sixteen phenylurea herbicides and their main metabolites in amended soils 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 initial single phase extraction of soil sample with acetonitrile by sonication, followed by liquid-liquid partitioning formed by addition of NaCl. The average recovery by the LC-MS² method obtained for these compounds varied from 76.2 to 107.9% with a relative standard deviation ranging from 2.1 to 5.8%. The method presents good linearity (R²>0.99) over the range assayed 10-1000 μg L⁻¹ (except N-phenylurea 50-1000 μg L⁻¹). The detection limits for the compounds studied varied from 0.1 to 9.0 ng g⁻¹.