Abstract:
After removing impurities, crushing, air drying, and sieving the soil sample, an aliquot (10 g) was taken, and 10 mL of water (infiltrating the sample) was added. Then, 5 g of sodium chloride and 20 mL of acetonitrile were added, and the mixture was mixed well and centrifuged for 3 min. The 10 mL of the organic layer was taken and passed through an activated HLB solid phase extraction column at a flow rate of 10 mL·min
−1, and 5 mL of methanol-dichloromethane mixed solution at a volume ratio of 1∶1 was used for elution. The eluate was collected, and blown to near dryness at 50 ℃ with nitrogen. The residue was dissolved in 1 mL of ethyl acetate, and the solution was passed through a 0.22 μm organic filter membrane. The filtrate was determined by gas chromatography-tandem mass spectrometry. In chromatographic analysis, HP-5MS column was used as the stationary phase for separation under the column heating program. In mass spectrometry analysis, electron impact ion source was used for ionization, multiple reaction monitoring mode was used for detection, and external standard method was used for quantification. It was shown that linear relationships between values of the mass concentration and corresponding quantitative ion peak area of 7 pyrimidine fungicides (
cyprodinil,pyraclostrobin,pyrimethanil,azoxystrobin,pirimiphos-methyl,fenarimol and mepanipyrim) were kept in the range of 0.005-0.5 mg·L
−1, with detection limits (3S/N) in the range of 0.004 1-0.008 4 mg·kg
−1. Test for recovery was made according to the standard addition method, giving recoveries in the range of 86.3%-110%, and RSDs (
n=6) of the determined values were all less than 5.0%. The proposed method was used for the analysis of 5 actual samples, and cyprodinil and pyrimethanil were detected in two samples, with detection amounts of 0.032, 0.051 mg·kg
−1, respectively.