The Preparation Of Surface Enhanced Raman Scattering Substrate And Its Application In Pesticide Residues Detection

In recent years, more and more attention has been paid to the problem of pesticide residues, while Surface enhanced Raman spectroscopy has its unique advantages in the field of pesticide residues detection for its rapid, simple and highly sensitivity detection characteristics.The key of surface enhanced Raman scattering technique is the preparation of the substrate. The silver sol and gold sol were prepared by sodium citrate reduction method. The optimum preparation conditions were discussed in detail: Silver nitrate and sodium citrate were mixed in 1:4 molar ratio,heating 14 minutes under the condition of ph=3; Gold nitrate and sodium citrate were mixed in 2:3 mass ratio, heating 15 minutes under the condition of ph=4. The optimization of the spatial configuration and the calculation of the theoretical Raman spectra were done by density functional theory using 6-31 G basis set for lambda-cyhalothrin and bifenthrin respectively, and good agreements were obtained between the theoretical and experimental results. Vibration modes were assigned to part of Raman characteristic peaks in the range of 400~1800 cm-1for lambda-cyhalothrin, 400~1500 cm-1for bifenthrin. Finally with kumquat as the research object, Raman spectra of 45 different concentrations of two pesticides were obtained. The research results showed that the models built by synergy interval partial least squares(siPLS) combined with baseline data preprocessing and wavelet denoising were ideal for both of two pesticide residue solution.The RP(Correlation coefficient) was 0.9979, the RMSEP(root mean aquare error of prediction)was 1.6531 mg/L for lambda-cyhalothrin and the RP was 0.9931, RMSEP was 1.7142 mg/L for bifenthrin.