Exploration Of Rapid Measurement Of Pesticide Residue Based On Infrared Spectroscopy

How to detect pesticide residual in food quickly and efficiently is a key problemin food safety controlling system. The conventional methods need complicatedsample pretreatment, consume biochemical reagents and last a long measuring period.So we attempt to achieve the pesticide residual measurement by optical method. Thispaper is concentrated on the methodology study for direct measurement on vegetablepesticide residual, for it neither need sample pretreatment nor cause pollution. The paper consists of two aspects as follows: Firstly, a series of spectral experiments by transmission method and ATR methodhave been carried out to investigate the precision on solvents and neat pesticides madesamples, including the analysis of pesticide's absorption in vegetable juice; thetheoretical calculation and experimental analysis dichlorvos's optimistic pathlength bytransmission; the pesticide's detection accuracy on solvent samples by ATR method.Experimental results showed: at 2mm pathlength, the detection accuracy of dichlorvosis 4.4ppm, correlation is 0.9999; using ATR method, dichlorvos's SEP is 46.67ppmand correlation is 0.9978, trichlorfon's SEP is 32.52ppm and correlation is 0.964. Secondly, some experiments applying flat plate ATR system have been carried outto investigate the feasibility of direct measurement on vegetable samples, includingthe analysis of direct measurement effecting aspects on vegetable; vegetable simulatorchoosing and detection accuracy evaluation; applying data pretreatment methods toevaluate the repetition of ATR system. Experimental results showed: vegetablesimulator's SEP is 105.28ppm, correlation is 0.9998; about repetition, the simulator'sCV value changed form the original 0.0067 to 0.0046 thorough averaging 15 times,the vegetable sample's CV value changed form the original 0.026 to 0.024 throughsmooth and to 0.0059 through normalization at 3257cm-1 water's absorption peak. We come to the conclusion that, mid-infrared spectroscopy can be applied to fastrough selection of over used samples. By building models for some certain kind ofpesticides, the rapid and direct detection can be achieved. But restrained by the ratherlow sensitivity of IR instrument, accurate quantitive detection couldn't be realize yet.