Determination of monosulfuron-ester residues in grains, straw, green plants and soil of wheat by modified QuEChERS and LC-MS/MS

Abstract

Monosulfuron-ester is a novel sulfonylurea herbicide and has potent selectivity in controlling weeds such as goosefoot and climbing bindweed. In the present study, a fast and sensitive modified QuEChERS (quick, easy, cheap, efficient, rugged and safe) method to determine monosulfuron-ester in grains, straw, green plants and soil of wheat has been developed. The milled sample in acetonitrile was shaken for 0.5 h to perform a fully analyte extraction. Then the extract was cleaned up by dispersive solid phase extraction (DSPE) with different sorbents, and subsequently determined by liquid chromatography tandem mass spectrometry (LC-MS/MS). The method exhibited excellent linearity (R² ≥ 0.996) for the monosulfuron-ester in the four matrices. The limits of detection (LODs) ranged from 0.1 to 2.0 μg kg⁻¹. The average recoveries in grain, straw, green plant and soil at three levels ranged from 76.1 to 100.0% with relative standard deviations (RSDs) less than 10.0%. No residues were detected at harvest time in the samples of grain, straw and soil treated post-emergence at up to 45 g active ingredient (a.i.) ha⁻¹. A mathematical model describing residue dissipation over time after post-emergence treatment was given for the green plant and soil, respectively.