Study On Qualitative And Quantitative Analysis Methods Of Pesticide Residues By Surface-Enhanced Raman Spectroscopy (SERS) Using Silver Colloid

Since Fleischmann found the Surface-Enhanced Raman Spectroscopy (SERS) of pyridine molecule which absorbed in the roughed silver electrode in 1974, the technology of SERS had developed very fast in a wide variety of applications such as pharmaceutical analysis, environmental pollutants control and biological sample analysis because of its higher sensitivity and rapidness. The main work of this thesis is to develop a method which is about qualitative analysis of pesticide mixture and determination of tricyclazole content in paddy rice by Surface-Enhanced Raman Spectroscopy (SERS).Ag colloid was prepared to get the SERS of tricyclazole, paraquat and flusilazole. The enhancement factor of Ag colloid which was estimated to tricyclazole reached 2.11×106. Aqueous samples could be detected by SERS in low concentrations of 0.01 mg/L,0.1 mg/L and 2.85 mg/L for individual tricyclazole, paraquat and flusilazole respectively. When mixing the three pesticides in the low concentrations, their characteristic peaks could still be identified from the SERS spectrum of the mixture. Pyridine was selected as an internal standard to the quantitative detection of tricyclazole. The correlation between It/Ip and concentration of tricyclazole showed significant linear relationship with a correlation coefficient of R2=0.995 in a concentration range of 0.05-0.70 mg/L and the tricyclazole solution could be detected to be low as 0.002mg/L by SERS. The method was applied to determine tricyclazole contents of three real rice samples with a standard addition method in order to eliminate interference of the matrix. The mean errors of SERS measurements for the three samples of Wanjing #6, Fengliangyou #2, Yanjing #2 were 0.0146,0.0019 and 0.0203 mg/Kg respectively, compared with the results obtained by HPLC method. This also showed a good reproducibility with low values of relative standard deviation (RSD) (n=3) for the three samples ranged from 3.63% to 4.64%. When detecting triabendazole and diqat with silver colloid as SERS substrate, the concentration of the two pesticides can be as low as 0.054mg/L, 0.05mg/L respectively.