A rapid, sensitive and simultaneous analysis of 395 pesticides was developed in soybean using gas chromatography-tandem mass spectrometry (GC-MS/MS). The scheduled multiple reaction monitoring on GC-MS/MS was optimized with electron ionization mode. Method limit of quantitation (MLOQ) was 0.01 mg/kg, and 390 (98.7%) of the total pesticides satisfied this criterion with signal to noise (S/N) ratio greater than 10 on the chromatogram. For the evaluation of linearity of calibration, matrix-matched standards ranging from 0.002 to 0.2 mg/kg was injected on GC-MS/MS (2 μL) and the correlation coefficient (r2) of each pesticide was verified. Among the pesticides, 390 (98.7%) was r2 ≥0.990, showing the excellent linearity within the linear ranges. For the recovery tests, blank soybean (10 g) was treated with pesticides and extracted with 20 mL of acetonitrile. The sample was filtered under vacuum, and the extract solution was treated with 3 g of sodium chloride, and then centrifuged. The supernatant (8 mL) was evaporated and optionally partitioned with acetonitrile-hexane procedures to remove lipid matrices. The acetonitrile layer was evaporated again and subject to cleanup with florisil SPE (500 mg), and then the final extract was injected on GC-MS/MS for analysis. Among the 395 target analytes, the numbers of pesticides satisfying recovery range of 70-120% (RSD ≤20%) were 324 (82.0%, 0.01 mg/kg) and 325 (82.3%, 0.05 mg/kg) when excluding acetonitrile-hexane partitioning, and 293 (74.2%, 0.01 mg/kg) and 287 (72.7%, 0.05 mg/kg) when including partition step. The averages of matrix effect for 395 pesticides were 7.4% without partitioning step and 6.8% with partitioning step. This established methods will be able to support the monitoring of multiresidues in soybean.

Development of simultaneous muliresidue analysis for 395 pesticides in soybean using gas chromatography-tandem mass spectrometry

256th National Meeting (2018)

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