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Determination of thiamethoxam in fruit by high performance liquid chromatography-mass spectrometry/mass spectrometry

Objective To establish an easy, rapid and sensitive method to determine thiamethoxam pesticide residues in fruit by utilizing liquid chromatography-mass spectrometry/mass spectrometry(LC-MS/MS). Methods Fruit sample 5 g with 20 m L acetonitrile was extracted in the condition of ultrasonic oscillation, then the extract was purified by dispersive solid phase extraction using 20 mg carb and 60 mg PSA as purification sorbent and determined by LC/MS/MS. Results A good separation for thiamethoxam was achieved, with a correlation coefficients about 0.9999. The detection limit of the method was 0.3 μg/kg. The average recoveries of thiamethoxam ranged from 88.9% to 100.3% in the range of 0.01 mg/kg, 0.05 mg/kg and 0.10 mg/kg in apple, pear and peach, and the relative standard deviation(RSD) was between 1.98% and 4.53%, respectively. Conclusion The method is simple, rapid and sensitive, with a good purifying effect and a high recovery rate, which is suitable for the detection and security monitoring of the thiamethoxam in fruit.