Residue and risk assessment of fluopicolide and cyazofamid in grapes and soil using LC-MS/MS and modified QuEChERS

The residue behavior of fluopicolide, cyazofamid and their metabolites (M-01, M-02 and CCIM) was evaluated in open field conditions. The dissipation and terminal residue of these five compounds were determined via a modified QuEChERS method, by adjusting the liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) conditions and optimizing the purification process. This led to a satisfactory average recovery of between 71.6% and 107.7%, as well as limit of quantitation (LOQ) values of 0.05 mg kg^-1. The dissipation results recorded in two places in China illustrated that the half-life values of fluopicolide are 11.4 (Anhui, grape), 19.7 (Anhui, soil) and 21.8 (Hebei, grape), 21.2 (Hebei, soil) days, respectively. As for the dissipation of cyazofamid, it was found to have half-life values of 8.7 (Anhui, grape) and 20.1 (Hebei, grape) days. The final residues in grapes were found to be below the maximum residue limit (MRL) of 2 mg kg^-1 for fluopicolide and 1 mg kg^-1 for cyazofamid. Thus, a preharvest interval of 10 days and recommended MRLs from the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) are appropriate to ensure the food safety of fluopicolide and cyazofamid in grapes. The hazard quotient (HQ) and acute hazard index (aHI) values were found to be below 100%, demonstrating negligible risk in consuming grapes, regardless of long or short-term exposure.