Rapid Detection Of Agricultural Pollution Based On Libs And Sers Technology

Fast and reliable on-site detection is of great significance to the monitoring and management of agricultural pollution such as heavy metals in soil and pesticide residues in fruits or vegetables.Laser Induced Breakdown Spectroscopy(LIBS)enables simultaneous analysis of multiple elements,and can accomplish rapid detection of multiple heavy metals in soil.Non-destructive testing of surface-enhanced Raman spectroscopy(SERS)has unique advantages in the detection of agricultural products such as fruits and vegetables.Both of these detection techniques are simple to operate,low-cost,and without the need for complex sample preparation,which can well meet the demand of rapid field testing.Therefore,the research of LIBS and SERS technology has important practical value.The current status of agricultural pollution in China was introduced first,emphasizing the need for rapid detection of hazardous chemicals.And the LIBS technology for simultaneous detection of heavy metals in soil and SERS technology for non-destructive testing of fruits and vegetables were pertinently proposed.Based on the theoretical analysis,a reliable LIBS measurement system was set up from the aspects of optical design,machine debugging and performance testing.The spectral measurement range was 337-453 nm and the resolution was 0.1 nm.The system was applied to the detection of soil samples containing heavy metal Cr,the elemental components were qualitatively analyzed according to LIBS spectroscopy.Spectral data was pretreated by peak-areas normalization and the different concentrations was classified by PCA method.The relationship between spectral intensity and elemental concentration was established by univariate analysis,and the fitting correlation coefficient was 0.9857.Multiple regression analysis was further studied to reduce the impact of interference,the fitting correlation increased to 0.9987.The above studies verified the feasibility of LIBS quantitative analysis for heavy metals in soil.In the detection of pesticide residues,a SERS filter paper substrate decorated with Ag nanoparticles was designed.The preparation method,storage time and sensitivity were explored.Rapid sampling by wipe was achieved because of the adsorption of filter paper,and the optimal wipe time was about 15s.A three-step"drop-rub-test"method was established to measure the thiram concentrations in apple,pear and grape.The calculated limits of detection were 4.6261,5.1799 and 5.7061 ng/cm~2,respectively.The results indicate the reliability and practicability of SERS technology in this paper.