Determination of Six Sulfonylurea Herbicide Residues in Soybeans by HPLC-MS

A high performance liquid chromatography/electrospray ionization mass spectrometry method at the selective ion monitoring mode has been developed for the simultaneous determination of six sulfonylurea herbi-cide residues in soybeans.Sulfonylurea herbicides were extracted with acetonitrile,followed by hexane parti-tioning.After the extract was cleaned up with florisil column,sulfonylurea herbicides were analyzed by HPLC-ESI(+)-MS and quantified by external calibration method.The linear range was from0.025to 1.0μg/mL,and the correlation coefficients were0.9996-0.9997.The average recoveries of six sulfony-lurea herbicides in spiked soybeans ranged from72%to99%,and the relative standard deviations were be-tween0.9%and7.7%.The detection limit of this method was10μg/kg.