A simultaneous multiresidue analysis for 203 pesticides in soybean using florisil solid-phase extraction and gas chromatography-tandem mass spectrometry

A multiresidue analysis method for the simultaneous determination of 203 pesticides in soybean was developed using solid-phase extraction (SPE) and gas chromatography-tandem mass spectrometry (GC-MS/ MS). Scheduled multiple reaction monitoring by GC-MS/ MS was optimized in electron ionization mode. The target pesticides satisfied the method limit of quantitation below 0.01 mg/kg, and an excellent instrumental repeatability was obtained. The calibration curve correlation coefficients (r(2)) for 201 (99.0%) pesticides were >= 0.990. The Multiclass Pesticide Multiresidue Method (No. 2) of the Korea Food Code was scaled down and applied for efficient sample treatment. Soybean sample (10 g) was extracted with 20 mL acetonitrile. The sample was filtered, partitioned with sodium chloride, and centrifuged. The supernatant (8 mL) was subjected to cleanup with a florisil SPE cartridge (500 mg), and the final extract was subjected to GC-MS/MS analysis. To remove fat, further liquid-liquid partitioning with n-hexane/acetonitrile was conducted before the SPE cleanup, and this procedure was compared to the non-partitioning procedure. The percentage of pesticides satisfying the recovery range of 70-120% with a relative standard deviation <= 20% in the non-partitioning and partitioning procedures were 87.2% and 78.8% at 0.01 mg/kg and 88.2% and 76.8% at 0.05 mg/kg, respectively. The average matrix effect value (%) was 5.5%. This miniaturized analytical method can be successfully applied for rapid and sensitive monitoring of multiresidues in soybean and related agricultural products.