Research On The Detection Of Three Toxic Residues In Agricultural Products Based On SERS Technology

In recent years,food safety problems represented by the safety of agricultural products have emerged in endless and repeatedly,causing great harm to the health of the people throughout the country.How to effectively detect toxic residues in agricultural products has become an important issue facing our country.Since the 1990 s,Surface-Enhanced Raman Scattering(SERS)technology has been extensively researched and developed rapidly.Compared with traditional detection methods,SERS technology is simpler and faster to operate.It has great application value in the qualitative and semi-quantitative detection of toxic residues in agricultural products.In this paper,based on SERS technology,SERS detection and semiquantitative analysis were performed on the three toxic residues of phosmet,thiram and auramine O in different agricultural products.Firstly,based on the density functional theory(DFT),B3 LYP method of the Gaussian09 software was used to optimize the molecular structure of our research objects: phosmet,thiram,and auramine O,and to perform the theoretical calculation of Raman spectroscopy.After that,the Raman spectrum obtained by the theoretical calculation was compared with the conventional Raman spectrum and SERS spectrum obtained from the actual measurement,and then the vibration modes of three kinds of toxic residual Raman characteristic peaks were assigned.Then,silver colloid and silver colloid-based filter paper SERS substrates were prepared by chemical reduction and liquid/liquid interface self-assembly technology.And the morphology,size and ultraviolet absorption spectra of the silver nanoparticles in the silver colloid were characterized by Scanning electron microscope(SEM),Ultraviolet and visible spectrophotometry(UV-Vis)and dynamic light scatterometer.At the same time,the background noise,stability and sensitivity of two kinds of reinforced substrates were characterized by SERS detection with rhodamine 6G as a test probe.Thirdly,phosmet on the surface of the tomato,the thiram of cucumber,and the auramine O of durian were detected by using filter paper SERS substrate through wipe and direct detection.The detection limits are 1 ?g/m L,1 ?g/m L,and 0.5 ?g/m L,respectively,which proved the feasibility of using SERS technology for on-site rapid detection.Finally,the SERS detection was performed on phosmet in tomato,thiram in cucumber,and auramine O in durian using the silver colloid,and the semiquantitative analysis and recovery rate were measured.The detection limits for phosmet in tomato,thiram in cucumber,and auramine O in durian are 2.5 ?g/g,1 ?g/g,and 0.1 ?g/g,respectively.The reproducibility of the detection method shows that the method has a high recovery rate of 94.4%~106.4%,95.1%~109.5% and 95.6%~108.8%,respectively.The results show that the SERS technology has great application prospects in the detection of toxic residues in agricultural products.