Abstract: A method was developed for the determination of thiophanate-methyl and carbendazim residues in cucumber and soil by using QuEChERS-high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The residues in the samples were extracted by acetonitrile, cleaned up by developed QuEChERS method, and then analyzed by using LC-MS/MS in multiple reaction monitoring (MRM) mode via positive electrospray ionization with an Agilent ZORBAX SB-C18 column (30 mm×2.1 mm, 5 μm) as the analytical column. The recoveries of thiophanate-methyl spiked at four levels of 0.01, 0.05, 0.1 and 1.0 mg/kg were from 87.3% to 96.0% with the relative standard deviations (RSDs) of 8.0%~9.3% in cucumber, from 88.8% to 93.4% with the RSDs of 5.3%~9.9% in soil; the recoveries of carbendazim spiked at the same levels as those of thiophanate-methyl were from 87.1% to 92.3% with the RSDs of 5.2%~7.5% in cucumber, from 85.8% to 90.9% with the RSDs of 5.3%~13.2% in soil. The method is simple, rapid and characterized with acceptable sensitivity and accuracy to meet the requirements of the pesticide residue analysis. This method is applicable to confirm the residues of thiophanate-methyl and carbendazim in cucumber and soil.

Key words: carbendazim, cucumber, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), soil, thiophanate-methyl, QuEChERS