Research On Permeation And Degradation Dynamics Of Dimethoate On Tea Tree And Spinach Leaves

The Dimethoate is an organophosphate systemic insecticide which is extensively applied in crop planting of our country.After spraying dimethoate,it is absorbed and transmitted by plant and enters into the inside of plant,meanwhile,it is digested and metabolized on the surface and inside of plant.The Omethoate which has characteristic of high toxic pesticides belongs to the rmetabolites of dimethoate.On the basis of the high toxicity of the Dimethoate and Omethoate,it is necessary to further study the digestion and metabolism process in agriculture productsIn this study,we have explored the feasibility of the SERS technology determine dimethoate pesticide residue on the surface of spinach.The degradation dynamics of dimethoate and the generation rule of omethoate in tea plants and the surface and inside of spinach leaves have been studied.The specific study details are as follows:(1)Determination the method of SERS rapid qualitative and quantitative the dimethoate pesticide residues on spinach surfaceThe gold nanoparticles were selected as the enhancing agent of the dimethoate leguemann spectra,the characteristic peak 906 cm-1of the dimethoate was determined as the judgment basis of qualitative quantitative analysis.The linear equation for different concentrations of dimethoate pesticide was Y = 1549.5 X + 2024.5,the correlation coefficient R-squared was 0.9661.Validation research by using UPLC/MS/MS technology,the two methods which detected dimethoate pesticide residue on the surface of spinach after different time picking pesticide application were consistent with first order kinetics equation: Ln R = 0.195 + 2.5087 d and Ln R = 0.168 d + 2.3932;The correlation coefficient R was 0.9829 and 0.9759 respectively;Half-life was 3.55 days and 4.13 days;The correlation equation of two methods was Y = 0.9212 X,correlation coefficient was 0.9055.It have proved that the SERS technique could be applied in the study of degradation dynamics dimethoate pesticide residue on surface of spinach.(2)Comparative study the degradation dynamics of dimethoate and the generation rule of omethoate the greenhouse tea plant leaves and the surface and inside of spinach leaves.The degradation dynamics of dimethoate was conformed with the first order dynamic equation,it was Ln R =-0.365 d + 3.3553 and Ln R =-0.195 d + 2.5087 respectively;The correlation coefficient R was 0.9944 and 0.9829.Omethoate generation conditions had significant differences on two kinds of plant leaf surface.The generation production of omethoate were increased with extension of time on the surface of tea plant leaf while omethoate had not generated on the surface of spinach.The variation tendency of dimethoate residues was increased at first and then decreased in the inside of leaf,it reached maximum 0.88 ?g and 0.17 ?g at 10 th day and5 days in tea plant leaf and spinach leaf,respectively;The internal tea plant residual was greater than the interior spinach leaves.Both plant leaves interior had produced omethoate and also had increased at first and then decreased tendency,and reached maximum0.0467?g and 0.28?g at 10 th days and 14 th days respectively.(3)The study of changes tendency the dimethoate pesticide residue ratio in the interior of tea plant and spinachWith external dimethoate residual value division internal dimethoate residual value as the research object,the residual ratio decreased with time,the external residue is internal residual 672 times and 576 times at first day respectively,the external residue is internal residual 9 times and 12 times respectively at 14 th day.This study provided new ideas for selecting the suitable method and reducing pesticide residues after post-mining.