A rapid multi-residue determination method of herbicides in grain by GC-MS-SIM

In this study, a gas chromatography-mass spectrometry method is successfully developed for the determination of 11 herbicide residues (alachlor, acetochlor, butachlor, pretilachlor, metolachlor, dimethenamid, propachlor, napropamid, propanil, atrazine, and metribuzin) in rice and soybeans. The sample is extracted with acetone-water, degreased by liquid-liquid partition, and purified through solid-phase extraction with Florisil. Experiments on 5 fortification concentrations are carried out, and the limit of determination is 0.02 mg/kg. The average recoveries of soybean samples range from 63.3% to 96.0%, and the relative standard deviations are from 2.14% to 11.2%. The average recoveries of rice samples range from 76.8% to 102% and the relative standard deviations are from 2.2% to 9.08%. The results indicate that the method developed is fast, accurate, and easy to operate. It also demonstrates that the method can meet the requirements of simultaneous determination of 11 herbicides in rice and soybeans.