Dissipation, residue and dietary risk assessment of difenoconazole in Rosa roxburghii

Rosa roxburghii is a medicinal and edible plant, which is favored by consumers due to its rich vitamin C content. Residues and potential health risks of difenoconazole in the R. roxburghii ecosystem has aroused a concern considering its extensive use for controlling the powdery mildew of R. roxburghii. In this study, the residue of difenoconazole in R. roxburghii and soil was extracted by acetonitrile, purified by primary secondary amine and detected by liquid chromatography-tandem triple quadrupole mass spectrometry. The average recoveries in R. roxburghii and soil matrix varied from 82.59% to 99.63%, with relative standard deviations (RSD) of 1.14%-8.23%. The limit of quantification (LOQ) and detection (LOD) of difenoconazole in R. roxburghii and soil samples were 0.01 mg/kg. The dissipation of difenoconazole followed well the first-order kinetic, with a half-life of 3.99-5.57 d in R. roxburghii and 4.94-6.23 d in soil, respectively. And the terminal residues were <0.01-2.181 mg/kg and 0.014-2.406 mg/kg, respectively. The chronic and acute risk quotient values of difenoconazole were respectively 0.42% and 4.1%, which suggests that the risk was acceptable and safe to consumers. This study provides a reference for the safe and reasonable use of difenoconazole in R. roxburghii production.