The Detection Methods Analysis Pesticides Residue On Navel Orange By Sers

As the quality and safety issues of food are becoming the focus of attention bypeople, to explore a kind of detection with high precision, low environmentalpollution and fast food testing method is highly practical value. The technology ofSurface-enhanced Raman spectroscopy can be used in single molecule detection andthe detection of biological samples because of its super high sensitivity and selectivity.Selecting navel orange as the research object, used different SERS substrate,acquisition chlorpyrifos, dimethoate and phosmet surface enhanced Raman scatteringspectra of pesticide residue, and three kinds of pesticides were qualitative andquantitative analyzed. The main results of the thesis were involved:1. Different concentrations of omethoate standard solution were prepared,samples spectra were collected by confocal Raman spectroscopy and portable Ramanspectrometer respectively. Though the analysis of spectral data and found that theeffect of the confocal micro Raman spectrometer is better. omethoate standardsolution spray on navel orange skin, Raman spectra of omethoate were collected bythe confocal micro Raman spectrometer. Calibration models of omethoate solutioncontent were developed by partial least square (PLS) algorithm and the differentspectra pretreated methods. The results showed that the model built by PLS combinedwith the baseline data preprocessing was ideal, the correlation coefficient ofprediction (RP) was0.973, the root mean square error of prediction (RMSEP) was2.01%.2. Silver colloid was prepared to get the SERS of chlorpyrifos, dimethoate andphosmet on the surface of navel orange. chlorpyrifos, dimethoate and phosmetsolution samples could be detected by SERS in low concentrations of5mg/L. Thequantitative mathematical models of the three kinds of pesticide solutions wereestablished and different spectral pretreatment methods were compared. The resultsshowed that the model built by PLS combined with the multiplicative scattercorrection and first derivation data preprocessing was ideal for chlorpyrifos, the RP was0.843, the RMSEP was2.992mg/L; the model built by PLS combined with thebaseline data preprocessing was ideal for dimethoate, the RPwas0.936, the RMSEPwas1.706mg/L; the model built by PLS combined with the second derivative datapreprocessing was ideal for phosmet, the RPwas0.852, the RMSEP was5.177mg/L.3. The Klarite substrates were prepared to get the SERS of phosmet on thesurface of navel orange. The quantitative mathematical models of phosmet solutionswere established. The results showed that the RPwas0.963, the RMSEP was6.424mg/L.4. Silver colloid and the Klarite substrates were prepared to get the SERS ofresidual pesticides on the surface of navel orange. In the qualitative analysis ofpesticide residue，the two kinds of base has a good effect. In quantitative analysis，thereproducibility and stability of SERS used the Klarite substrates were better. Butproduction of silver colloid is simpler and its price is low. The results indicate thatanalysis of pesticide residue by SERS is feasible.