Residue dynamics and safety evaluation of hexaconazole in kiwifruit

In order to study the residual characteristic and safety of hexaconazole in kiwifruit, an analytical method was developed for the determination of hexaconazole residue in kiwifruit. The dissipation dynamics and final residues of hexaconazole in kiwifruit were investigated by this method. A simple and efficient pretreatment method called QuEChERS was used. Samples were extracted with acetonitrile and analyzed by ultra performance  liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). And the external standard and peak area method were employed for the quantitative analysis. Residual dissipation dynamics and final residue levels of hexaconazole in kiwifruit from six experimental sites (Yantai in Shandong Province, Yuncheng in Shanxi Province, Xianyang in Shaanxi Province, Wuhan in Hubei Province, Suzhou in Anhui Province and Jiulongpo in Chongqing) were determined. The results showed that the dissipation of hexaconazole in kiwifruit was rapid, with half-lives of 13.9-17.8 d. The residual contents of hexaconazole in kiwifruit decreased according to the first-order kinetics equation. The chronic dietary intake risk assessment results indicated that the national estimated daily intake (NEDI) of hexaconazole in all kinds of food was 1.6902 μg/(kg bw·d), and the risk quotient (RQ) was 0.338, which demonstrated that hexaconazole applied to kiwifruit had low risk. If kiwifruit was sprayed 3 times with 75 mg a.i./kg of 30% hexaconazole SC, 21 days after the last spraying, the residue of hexaconazole in kiwifruit had low risk for dietary. Therefore, the recommended safe interval of 30% hexaconazole SC in kiwifruit was recommended to be 21 days.