Rapid Detection And Identification Of Pesticides Of Fruits And Vegetables Based On Infrared Micro-imaging

In agricultural production, the pesticides-caused environmental pollutionas well as the harm caused to human health by residual pesticides isconstantly aggravating due to the massive and unreasonable use of pesticides.This issue has attracted a great deal of attention from all circles of society andis coming on global focus. Therefore, world governments formulate theincreasingly strict pesticide residue limits, and develop the detectiontechnologies of pesticide residues accordingly.Infrared micro-imaging technique is a kind of rapid, nondestructive andnon-polluted detection technique, which also has the advantages of theimage-spectrum combined, micro-area partition, visualization, high-accuracy,high-sensitivity and so on. It’s a powerful method to understand the spatialdistribution and the molecular composition of complex materials. Infrared micro-imaging system was as a testing tool, and Cypermethrin, Chlorpyrifos,Abamectin were as research objects in this paper. It launched qualitative andquantitative studies for pesticide residues on the surface of fruit and vegetablesamples and biological pesticide adulteration and recognition. The infraredmicro-image features of Chlorpyrifos, Cypermethrin and other pesticideswere analyzed in the paper. The results got the main molecular structure ofCypermethrin, Chlorpyrifos and its characteristic absorption peaks in theinfrared spectral region. Therefore, it provided feasibility study for thetechnology which used in apple skin sprayed with Cypermethrin andChlorpyrifos solution.The apple skins that sprayed with single component pesticide werestudied. The results show that with the decrease of concentration of twopesticides, the numbers of the characteristic absorption peaks which attributedto both pesticides reduced in turn. And the numbers of characteristicabsorption peaks which shifted increased in turn. At the same time with thereduction of the concentration of two pesticides, the interference of apple’sown composition and water content to detection enhanced.So that thedetection sensitivity of IR micro-imaging technique decreased. Thedifferences of distribution information of Cypermethrin and Chlorpyrifos onapple skin were easily and quickly seen by compare correlation images.The apple skins sprayed with pesticide mixtures were studied on the basis of single component pesticides. The co-existence of Cypermethrin andChlorpyrifos was detected by IR spectra and second derivative spectra ofapple skin which sprayed with three different concentrations and differentproportions of Cypermethrin and Chlorpyrifos mixed solution. In addition,with the decrease of concentration of pesticide mixtures, the total number ofcharacteristic absorption peaks reduced in turn. With the increase ofproportions of Chlorpyrifos in pesticide mixtures, the numbers ofcharacteristic absorption peaks which belonged to Chlorpyrifos were moreand more. But the numbers of characteristic absorption peaks which belongedto Cypermethrin were fewer and fewer. It confirmed that the IRmicro-imaging technique was more sensitive in the areas of pesticideresidues.This study probed the different internal quality of fruit and vegetablesamples which impacted on the detection. The different water contents ofapple skin significantly affected the detection results. It was not good whenthe water contents were too high or too low. It was better when the watercontent was50%. The apple skin pigment certain affected the detectionresults. But specific impact was uncertain. It needed to be in-depth study. Thedifferences of vegetables leaf surface morphology certain impacted on thedetection. The application effect was better in relatively flat leaves. On thecontrary, the application effect was poor in relatively drape leaves. And the identification and detection technology of biological pesticidesadulterated with chemical pesticides was established based on IRmicro-imaging technique and ATR-FTIR technique for the first time. Thequalitative results showed with the increase in the proportions of Chlorpyrifoswhich was adulterated into Abamectin, the number of characteristicabsorption peaks belonged to Abamectin decreased gradually, and the peakintensity weakened. The number of characteristic absorption peaks attributedto Chlorpyrifos was just the opposite, and the peak intensity increasedgradually. The quantitative prediction models of Abamectin EC adulteratedwith Chlorpyrifos were established by partial least squares method andoptimized. And then the external validation sets was used to validation themodel performance. The quantitative results showed that ATR-FTIRtechnology can accurately determine the content of Abamectin EC adulteratedwith Chlorpyrifos. The model of prediction precision was improved throughspectrum pretreatment, outliers diagnosis and modeling parametersoptimization. The determination coefficient (R2(%)) was99.88. The rootmean square error of calibration (RMSEC), the root mean square error ofcross-validation (RMSECV) and the root mean square error of prediction(RMSEP) was0.44,0.79and0.70, respectively.In this study, it provided a new method for rapid detection of pesticideresidues of fruits and vegetables and rapid identification of biological pesticides adulterated with chemical pesticides. It laid a foundation for theapplication of IR micro-imaging technique and ATR-FTIR technology toqualitative and quantitative detection of pesticide residues and biologicalpesticides adulteration.