Simultaneous determination of seven herbicide residues in rice using QuEChERS-high performance liquid chromatography-tandem mass spectrometry Triple TOF

A multi-residue method was established to simultaneously determine seven herbicides (simetryn, isoproturon, bensulfuron methyl, anilofos, oxyfluorfen, oxadiazon and pendimethalin) in rice using QuEChERS and high performance liquid chromatography-tandem mass spectrometry Triple TOF (HPLC-MS/MS Triple TOF). The samples were extracted with a mixture of ethyl acetate and water (V_{ethyl acetate} : V_water = 80 : 20), purified by dispersive solid phase extraction with primary secondary amine (PSA), and detected by HPLC-MS/MS Triple TOF using the external standard method for quantitative analysis. Good linearity was achieved with a correlation coefficient of 0.99. The average recoveries of simetryn, isoproturon, bensulfuron methyl and anilofos ranged from 75% to 108% with the spiked levels of 0.001, 0.01 and 0.05 mg/kg. And the relative standard deviation (RSD) ranged from 1.1% to 7.0% (n  = 5). The limits of quantification (LOQs) of all those herbicides were 0.001 mg/kg. The average recoveries of oxyfluorfen, oxadiazon and pendimethalin ranged from 81% to 108% with the spiked levels of 0.01, 0.05 and 1 mg/kg. And the RSD ranged from 2.9 % to 9.0% (n = 5). And their LOQs were 0.01 mg/kg. This method is simple and rapid. Its sensitivity, accuracy and precision can meet the requirements of the pesticide residue analysis. Therefore, this method can be applied to the simultaneous analysis of simetryn, isoproturon, bensulfuron methyl, anilofos, oxyfluorfen, oxadiazon and pendimethalin in rice.