Research On The Vegetable Pesticide Residue Detection Using The Enhanced Raman Spectroscopy

In this paper,the routine test methods of pesticide residues are summarized firstly.Raman spectroscopy is introduced in detail and SERS is introduced.The recent research of SERS at home and abroad is reviewed.The influence of Au polymer adsorption sites on amitrole and cyromazine Raman spectra is studied.The optimum coordination position of N atom and Au atom is calculated by the electrostatic potential distribution on the molecular surface.Based on DFT,the B3LYP basis sets and 6-31++G(d,p)(C,H,N)/Lanladz(Au)basis set are used to calculate the two pesticide molecules of amitrole and cyromazine.DFT calculation data shows that when more and more Au atoms are added,the atomic clusters formed by the coordination system of pesticide molecules and gold nanoparticles become closer,and the enhancement effect of Raman spectrum is more significant.By using FDTD,the distribution of electric field intensity nearby Au nanoparticles,Au nanoparticle arrays and tips coated with Au are calculated.The theoretical simulation calculation shows that Au nanoparticles have better SERS enhancement ability on Al substrate than on Si substrate.With the increase of the size of Au nanoparticles and the decrease of Au nanoparticles array spacing,the enhancement effect of electric field is more significant.As the tip diameter of the tip increases,the enhancement effect of electric field is more significant.For the length of 250 nm tip,the electric field enhancement effect is better.The residues of amitrole and cyromazine in Chinese cabbage are qualitatively and quantitatively analyzed by SERS.Firstly,the Raman spectra in powder state and theoretical calculation are compared.The characteristic peaks of pesticides can be observed at the concentration of 1mg/L with gold colloid as the reinforced substrate.Based on the 726cm^-1characteristic peak,a quantitative analysis model of pesticide amitrole residue in Chinese cabbage is established,and the correlation coefficient is 0.986.Based on the 624cm^-1characteristic peak,a quantitative analysis model of pesticide cyromazine residue in Chinese cabbage is established,and the correlation coefficient is 0.980.