Research On SERS Rapid Detection Method Of Pesticide Residues In Rice Field Environment

Rice is the main food crop in China.The utilization rate of pesticides in rice fields is low,and a large amount of pesticides remain in the soil and water.In order to effectively reduce the environmental pollution of rice fields,the detection of pesticide residues is of great significance.Traditional detection methods are mainly chromatography and chromatography-mass spectrometry,which are time-consuming and laborious.Spectral detection is fast and efficient,but it has strong limitations due to its high detection limit.Surface enhanced Raman spectroscopy(SERS)is a novel,highly sensitive and rapid detection method,which has a good application potential in the field of environmental pesticide residue detection.In this study,the SERS technology was used to detect the residues of thiamendazole and tricyclazole in rice soil and water.By optimizing the SERS active substrate and the detection conditions of two pesticide residues,the detection of thiamendazole and tricyclazole pesticide residues in the rice planting process was realized.The main conclusions are as follows:(1).Research on SERS active substrate for pesticide residue detection:Control the amount of trisodium citrate to synthesize gold nanoparticles(Au NPs)with different particle sizes,and determine the most suitable Au NPs colloid substrate for SERS signal enhancement of two pesticides.The results showed that:In the range of 10-85 nm,with the increase of the Au NPs particle size,the enhancement effect was significantly improved.The prepared Au NPs(85 nm)colloids was an excellent substrate for the sensitive detection of pesticide residues by SERS,and the detection limits of thiabendazole and tricyclazole standard solutions were as low as 0.01 mg/L,which could be used in follow-up research.(2).Research on SERS detection method of pesticide residues in soil:Optimize the Qu ECh ERS method for soil pesticide residue detection,and realize rapid detection of pesticide residues in soil by Qu ECh ERS-SERS method.The results showed that:Multi-walled carbon nanotubes as adsorption material could effectively reduce the interference of soil components on pesticide molecules.Within a certain concentration range,there was a good linear correlation between the characteristic peak intensity of thiabendazole and tricyclazole and their residues in soil.Partial least squares regression was used to analyze the characteristic peak spectrum bands of thiabendazole and tricyclazole in soil,and the coefficients of determination of the prediction set(R_p~2)could reach 0.9597 and 0.9768,respectively.The detection limits of thiabendazole and tricyclazole in soil could reach 0.087 mg/L and 0.01 mg/L,respectively.(3).Research on SERS detection method of pesticide residues in water:Use SERS technology to quickly and directly detect pesticide residues in water,and explore the SERS detection rules of pesticide residues in water based on different sample detection volume.The results showed that:The SERS signal of pesticide molecules in water detected directly was significantly stronger than that detected after acetonitrile extraction.As the sample detection volume increased,the saturation concentration decreased,the SERS signal of low-residue pesticide increased,and the detection limit decreased.There was a good linear correlation between the thiabendazole and tricyclazole residues in water and the peak intensity.The detection limits of thiabendazole and tricyclazole in water could reach 0.01 mg/L and 0.03 mg/L,respectively.(4).Research on the change of pesticide residues in soil and water during the rice planting process:Use the optimized SERS detection method to study the change of pesticide residues in soil and water during the rice planting process.The results showed that:As the rice planting time increases,the amount of pesticide residues decreased,and the amount of pesticide residues in the water was lower than that in soil.The soil and water for rice planting at different intervals(1-28 days)after application of pesticides were detected,and both pesticide residues could be detected.In the detection of the two pesticide residues in soil and water during the rice planting process,the characteristic peak intensity was weak,and the linear correlation between the residue and the peak intensity was poor.