Studies On The Residual Behavior Of Mesotrione Atrazine And Metolachlor In Maize

In the present study,a simple and rapid analytical method for simultaneous determination of mesotrione,atrazine and metolachlor residues in maize and soil has been established by using Ultra-high performance liquid chromatograph tandem mass spectrometry(UPLC-ms/ms).And then,the dissipation and terminal residue experiment of mesotrione,atrazine and metolachlor under filed ecocystem have been investigated in Tianjin city and Heilongjiang province.The analytical parameters including the linearity,precision and accuracy were firstly evaluated.The effects of different extraction method on the extraction yield were investigated.Under the optimal conditions,the mean recoveries for all the three target compounds in ensilage maize samples were 93.6 ~ 106.1 % with 0.51-~ 13.05 % relative standard deviations;The mean recoveries for all the three target compounds in maize grain samples were 83.0~98.4 % with 1.13-~6.59 % relative standard deviations;the mean recoveries for all the three target compounds in maize straw samples were 84.7~107.7 % with 1.15-~4.15 % relative standard deviations;and the mean recoveries for all the three target compounds in soil samples were 85.7~96.8 % with relative standard deviations from 1.37-~11.62 %.The limit of quantification(LOQ)for ensilage maize,maize grains,maize straw and soil were all 0.005 mg/kg,The field experiments of mesotrione,atrazine and metolachlor have been conducted in Tianjin city and Heilongjiang province between 2015-2016.The dynamic degradation results showed that the degradation of mesotrione,atrazine and metolachlor in maize and soil were all coincided with first-order kinetic equation.The half-lives of mesotrione in maize straw and soil were between 1.49~3.08 days and 3.37~7.71 days,respectively.The half-lives of atrazine in maize straw and soil were between 1.88~9.60 days and 2.00~6.17 days,respectively.The half-lives of metolachlor in maize straw and soil were between 5.19~6.67 days and 5.78~7.46 days,respectively.The teminal residue experiment results showed that the final residues of the mesotrione in soil were between 0.005 mg/kg and 0.008 mg/kg;and the ultimate residues of mesotrione in maize straw and maize were all below 0.005 mg/kg;the final residues of the atrazine in soil and miaze straw were between 0.005 mg/kg and 0.032 mg/kg;and the ultimate residues of atrazine in maize was below 0.005 mg/kg;the final residues of the metolachlor in soil were between 0.005 mg/kg and 0.023 mg/kg;and the ultimate residues of metolachlor in maize was below 0.005 mg/kg.Take all the above results into consideration,it can be safely drawn the conclusio n that the established rapid and simple method was well qualified for the determination of mesotrione,atrazine and metolachlor residues in maize and soil.The dissipation of mesotrione,atrazine and metolachlor were all quick in maize and soil matrix.The final residues of all the three target compounds in maize were all not detected and the amount of the final residues in maize straw and soil were all below 0.005 mg/kg.It revealed that it is safe to apply mesotrione,atrazine and metolachlor in maize field within the recommended dosage.