Qualitative And Quantitative Analysis Of Pesticide Residues In Tea Based On Paper Chip And SERS

Tea is a major import and export industry in our country and a major label for China.However,the extensive use of pesticides makes pesticide residues in tea very serious.Nowadays,many conventional parties have certain disadvantages for tea pesticide residue detection,which is complicated in operation and expensive.In order to enable on-site detection in real time,this study used surface enhanced Raman technology and microfluidic paper chip to carry out on-site detection of pesticide residues,and qualitative and quantitative analysis,to determine the qualitative and quantitative methods for pesticide residue detection.The research contents are as follows:(1)A qualitative analysis method for rapid detection of pesticide residues in tea using SERS technology and paper chips was explored.Principal component analysis was carried out on the spectral data of the three pesticides collected,and then supported by support vector machine(SVM),extreme learning machine(ELM),probabilistic neural network(PNN)and ? nearest neighbor method(KNN).Model the classification model and compare the modeling results.Compared with the best ELM,PNN and KNN classification models,the best SVM model shows excellent classification accuracy and stability,and can be used in the qualitative analysis model of pesticide residue detection in tea,where K = 5,c = 3.3755 and When g = 1.0241,the recognition rates of training and prediction were 97.32% and 100%,respectively.At the same time,three pesticides were well classified.(2)A quantitative analysis method for rapid detection of pesticide residues in tea using SERS technology and paper chips was explored.The SERS spectral peaks of different concentrations of chlorpyrifos solution based on tea extract were calculated by density functional theory,and six characteristic peaks of chlorpyrifos were selected:337,680,754,1041,1375 and 1575 cm-1.According to the characteristic peak characteristic information at 1041cm-1,a linear equation of different concentrations of chlorpyrifos pesticides in tea extract was established.The linear equation was y=17.032x+656.85,correlation coefficient: R2=0.9845,recovery rate of chlorpyrifos in tea: 89.12-96.82%,relative standard deviation: 1.65-8.75%.Four characteristicpeaks of carbendazim were selected by density functional theory calculation: 896,1056,1101 and 1465 cm-1.According to the characteristic peak characteristic information at 1465cm-1,a linear equation of different concentrations of carbendazim pesticides in tea extract was established.The linear equation is: y=350.49x+2701.8,correlation coefficient: R2=0.9917,the pesticide in tea The recovery rate in the range:88.16 ~ 95.93%,relative standard deviation RSD = 4.85 ~ 9.17%.Five characteristic peaks of deltamethrin were selected by density functional theory: 556,741,1079,1182 and 1568 cm-1.According to the characteristic peak characteristic information at741cm-1,a linear equation of different concentrations of deltamethrin pesticides in tea extract was established.The linear equation was y=5.9453x+797.93,correlation coefficient: R2=0.9924,cyanide in tea.The recovery rate of pyrethroid pesticides was86.13~94.17%,and the relative standard deviation(RSD)was 7.00~9.5%.