Determination of 6 Pesticide Residues in Grain Planting Soil by Gas Chromatography-Mass Spectrometry

After impurity removal, natural air drying, crushing and screening of the soil sample, 10.0 g of the soil sample was taken and placed in the accelerated solvent extraction tank, and extracted with about 10 g of diatomite and 33 mL of the mixed solution of ethyl acetate and n-hexane at a volume ratio of 1:1. The extract was purified by a purification tube containing 1 g of magnesium sulfate, 500 mg of N-propyl ethylenediamine (PSA) and 500 mg of C₁₈, and blown to near dryness by nitrogen at 45℃. The residue was dissolved with 1.0 mL of ethyl acetate, and passed through 0.22 μm filter membrane. The filtrate was introduced into the gas chromatograph, separated on Rtx-5MS quartz capillary column, and detected in the multiple reaction monitoring mode with a mass spectrometer equipped with an electron impact ion source. As shown by the results, linear relationships between values of peak area and mass concentration of triadimefon, diniconazole, triflumizole, propamocarb, carboxin and propiconazole were found in the same range of 0.05-5.0 mg·L^-1, with detection limits (3S/N) of 0.005, 0.004, 0.006, 0.006, 0.006, 0.006 mg·kg^-1, respectively. Tests for recovery were made on blank samples at three concentration levels by standard addition method, giving results in the range of 89.5%-101%. The blank spiked sample was determined 6 times in parallel by this method, with RSDs of the determined values less than 5.0%.