Study On Pesticide Residues In Fruits By Sers Based On Gold Colloid And Klarite Chip

With the continued development of social economy and living standards incountry, the problem of food safety has already caused the widespread attention ofconsumers. At present, the conventional detection methods of fruit pesticide residuehas complex sample pretreatment, longer detection time, higher costs and other issues,so research to explore a non-destructive, simple and rapid method for the detection ofpesticide residues has important practical value. Selecting Gannan navel orange as theresearch object, used phosmet, chlorpyrifos and dimethoate three kinds oforganophosphorus pesticides as the index of analysis, used different Surface-enhancedRaman spectroscopy (SERS) substrate, acquisition phosmet, chlorpyrifos, mixingpesticides (phosmet and chlorpyrifos mixed) and dimethoate surface enhanced Ramanspectroscopy, and spectral data collected were qualitative and quantitative analyzed.The main results of the thesis were involved:1. Using gold colloid as SERS substrates, enhanced spectroscopy of phosmet,chlorpyrifos pesticide residues in orange skin was collected by confocal Ramanspectroscopy produced by Bruker Company. Phosmet and chlorpyrifos solutionsamples could be detected by SERS in low concentrations of3mg/L and4mg/L,respectively. Pesticide original spectral data were processed by partial least square(PLS), principal component regression (PCR), multiple linear regression (MLR)modeling algorithms and the different pretreatment methods. The results showed thatthe model built by PLS combined with the savitzky gold smoothing and secondderivatives data preprocessing was ideal for phosmet, the correlation coefficient ofprediction (RP) was0.908, the root mean square error of prediction (RMSEP) was4.417mg/L; the model built by PCR combined with the baseline and MSC datapreprocessing was ideal for chlorpyrifos, the RPwas0.780, the RMSEP was6.006mg/L.2. Using gold colloid as SERS substrates and mixed pesticides of phosmet andchlorpyrifos as the research object, Raman mixing pesticides band assignment was analyzed by characteristic Raman peaks of single power pesticide. Mixing pesticidesSERS spectra, antisymmetric C=O stretching of1774cm-1belong to phosmet, N-cyclopropyl bending vibrations of342cm-1belong to chlorpyrifos. Ramanspectroscopy of mixing pesticides have the two peak, this can be explainedqualitatively identified to phosmet and chlorpyrifos through the two peak. Spectradata were collected from mixing pesticides of orange skin. Pesticide original spectraldata were processed by the different modeling algorithms (PLS, PCR), the differentpretreatment methods and the different bands. The results showed that the model builtby PLS combined with the first derivatives data preprocessing was ideal for mixingpesticide in200~620cm-1,830~1040cm-1,1250~2300cm-1interval, the RCwas0.975,the RMSEC was1.282mg/L; the RPwas0.909, the RMSEP was3.338mg/L.3. The Klarite substrates were collected SERS of organ phosphorus pesticidesdimethoate on the surface of navel orange. Pesticide original spectral data wereprocessed by the different modeling algorithms (PLS, PCR, MLR) and the differentpretreatment methods. The results showed that the model built by PCR combined withthe baseline data preprocessing was ideal for dimethoate, the RPwas0.927, theRMSEP was8.172mg/L.