Residual Degradation Of Famoxadone And Cymoxanil In Cucumber Soil And Its Dietary Risk Assessment

In order to fully and correctly understand the residual degradation of famoxdone and cymoxanil in cucumber and soil samples after 52.5%famoxadone·cymoxanil dispersible granules were applied on the ground,the analysis and determination methods of famoxadone and cymoxanil residues in cucumber and soil samples were studied and established by adding recovery experiments with high performance liquid chromatography.On the basis of field experiments in accordance with GAP criteria,the residue digestion of famoxadone and cymoxanil in cucumber was systematically studied,and reasonable suggestions for their use were put forward.Meanwhile,the dietary risk assessment of famoxadone and cymoxanil in cucumber was evaluated based on the final residue data of famoxadone and cymoxanil in cucumber.The main conclusions are as follows:（1）A method for the determination of oxazolone and cymoxanil in cucumber and soil samples was established,and the detection conditions were optimized.The results showed that the accuracy,precision and sensitivity of the method met the requirements of pesticide residue analysis and detection.（2）The degradation of famoxadone and cymoxanil in cucumber and soil conforms to the first-order chemical kinetics equation(C_t=C₀e^-kt),and famoxadone and cymoxanil cymoxanil are easily digestible pesticides in cucumber and soil.（3）52.5%famoxadone cymoxanil dispersible granules were applied three times and four times,respectively,with an interval of 7 days.Seven days after the last application,the residues of oxazolone and cymoxanil were less than 0.05mg/kg,which were lower than the MRL values of oxazolone in Cucumber（1.00mg/kg） and cymoxanil in Cucumber（0.50 mg/kg）stipulated in China.（4）Suggestions for rational use:52.5%famoxadone cymoxanil dispersible granules were diluted 761.9 times with water at the early stage of cucumber downy mildew（effective component concentration:413.4 ga.i./ha）,applied twice,with an interval of 7 days and a safe interval of 7 days（days after the last application）.（5）The estimated daily intake of famoxadone and cymoxanil in the general population was 0.28 mg and 0.16 mg,accounting for 74.30%and 20.02%of the daily allowable intake,respectively.This indicated that the contents of famoxadone and cyanuric cymoxanil in Cucumber did not pose unacceptable risks to human health.