Dissipation behavior, residue distribution and dietary risk assessment of chlorfenapyr and clothianidin in leek using RRLC-QqQ-MS/MS technique

Commercial suspension emulsion(SE) of(8% chlorfenapyr + 20% clothianidin), as a pre-registered product in China, was firstly investigated under Chinese open-field conditions. A MWCNTs-based QuEChERS method for simultaneous determination of chlorfenapyr and clothianidin in leek was established and validated through rapid resolution liquid chromatography triples quadrupole tandem mass spectrometry(RRLC-QqQ-MS/MS). Based on this method, the dissipation behaviors, residue distributions and dietary risk probability of these fungicides in leek from two representative locations in China in 2016, which were previously treated with these insecticides at the doses of 420–630 g a.i./ha twice applications, were further investigated for food safety. Dissipation behavior of chlorfenapyr and clothianidin in leek followed first-order kinetics with the half-lives of 2.9–7.2 days, and the highest residues(HR) of these insecticides in leek were below 0.3811 mg/kg and 0.2989 mg/kg, respectively, at the pre-harvest interval(PHI, 7 days). For dietary risk assessments, the risk quotients(RQs) of chlorfenapyr and clothianidin in leek were evaluated by comparing the value of national estimated daily intake(NEDI) with acceptable daily intake(ADI), based on the trials data under good agricultural practices(GAP) conditions. The results indicated that RQs of chlorfenapyr and clothianidin in leek were21.5% and 0.29%, respectively, which exhibited an acceptably low health risk to leek consumption. The current study could not only guide reasonable usage of the formulation, but also facilitate the setting of maximum residue limits(MRLs) of chlorfenapyr and clothianidin in leek for Chinese