Screening of 258 Pesticide Residues in Silage Using Modified QuEChERS with Liquid- and Gas Chromatography-Quadrupole/Orbitrap Mass Spectrometry

A method for the simultaneous screening of 258 pesticide residues in silage using modified QuEChERS combined with liquid chromatography (LC)- and gas chromatography (GC)- quadrupole-Orbitrap mass spectrometry (Q-Orbitrap/MS) has been developed. After hydration, the silage was homogenized with a 1% acetic acid-acetonitrile solution, and the extract was purified using C-18, PSA, and anhydrous magnesium sulfate. Finally, the sample was detected using LC/GC-Q-Orbitrap/MS, and quantified using an external standard method. The results showed that 258 pesticides had an excellent linear relationship in the range of 0.1-50 mu g L-1, and that the coefficients of determination (R-2 were more than 0.99. The screening detection limit (SDL) of silage was in the range of 0.5-50 mu g kg(-1), and the limit of quantitation (LOQ) was in the range of 1-50 mu g kg(-1). The accuracy and precision of the method were verified at the spiked levels of 1-, 2- and 10-times LOQ, and the recovery of 258 pesticides was in the range of 66.5-119.8%, with relative standard deviations (RSDs) of less than 20% (n = 6). This method was simple, rapid, and reliable, and could be applied to screen and quantify multi-pesticide residues in silage.