Simultaneous Determination of Residues of 6 Broad Spectrum Bactericidal Pesticides in Planting Soil by Gas Chromatography-Tandem Mass Spectrometry with Accelerated Solvent Extraction

The residues of the 6 broad spectrum bactericidal pesticides (pyraclostrobine, tebuconazole, flusilazole, fluconazole, trifloxystrobin and chlorothalonil) in planting soil were determined by the title method. Planting soil sample was randomly collect, removed impurities, dried by air, grinded and sieved, and an aliquot (10 g) was taken, and mixed with 5 g of diatomite. The mixture was grinded evenly, transferred to the accelerated solvent extraction pool, and extracted according to the set parameters at the extraction temperature of 70℃ by nitrogen. The extract was passed through the activated magnesiumtrisilicate solid phase extraction column, and the obtained eluate was blown to nearly dry at 70℃ by nitrogen, and diluted to 1 mL with n-hexane. The above solution was injected into the gas chromatograph, and the 6 pesticides were separated on Rtx-5MS chromatographic column under temperature-programmed conditions, detected by tandem mass spectrometry with electron impact ion source, and quantified by matrix matching method. It was shown that the 6 pesticides could be separated within 20 min, and their mass concentrations were linearly related with corresponding peak areas in the range of 0.05 -2.0 mg·L^-1, with detection limits (3S/N) in the range of 0.005-0.012 mg·kg^-1. Test for recovery was made by standard addition method, giving recoveries in the range of 89.3%-102%, and RSDs (n=6) of the determined values ranged from 1.8% to 4.0%.