Determination Of Multi-Organophosphate Pesticide Residues In Vegetables Through Molecularly Imprinted Solid-Phase Extraction Coupled To Gas Chromatography

Organophosphate pesticides can effectively control the insects in agriculture to improvethe productivity and quality of the crop. However, their widely use also gives rise to thepesticides residues on the plant, which are harmful to human health because of their potentialmutagenic and carcinogenic properties. To prevent the pollution of organophosphatepesticides residues, it is critical to develop a simple, rapid and sensitive method for thedetermination of pesticide residues.In this study, a molecularly imprinted polymer was prepared and exhibited goodrecognition and fast adsorption ability toward multiple organophosphate pesticides. Twonovel methods for simultaneous determination of multiple organophosphate pesticidesresidues in vegetables was developed by utilizing molecularly imprinted solid-phaseextraction coupled to gas chromatography.1. MISPE-GC for the determination of trichlorfon and monocrotophos residuesIn this study, a molecularly imprinted polymer was prepared using the mixture oftrichlorfon and monocrotophos as the mixed-template, methacrylic acid as the functionalmonomer, and ethylene glycol dimethacrylate as the cross-linker. The imprinted polymer wascharacterized, and exhibited good recognition ability and fast adsorption-desorption dynamictoward the trichlorfon and monocrotophos. Using this imprinted polymer as sorbent, a newmethod of molecularly imprinted solid-phase extraction coupled to gas chromatography forthe determination of trichlorfon and monocrotophos residues in vegetables was developed.The factors affecting the solid-phase extraction were optimized. At a loading flow rate of2.0mL·min^-1for loading100mL, the detection limits were0.28μg·L^-1for trichlorfon and0.09μg·L^-1for monocrotophos, the peak area precision （RSD） for five replicate was4.23%to4.50%. The blank rape samples spiked with two organophosphate pesticides were determinedby this method with recoveries ranging from89.41%to95.12%. Moreover, this method was successfully applied to the quantitative detection of the trichlorfon and monocrotophosresidues in leek samples which were randomly purchased from the market.2. MISPE-GC for simultaneous determination of eight organophosphate pesticidesresiduesIn this study, a new molecularly imprinted polymer was synthesized using O,O-dimethylthiophosphoryl chloride, an intermediate for the manufacture of organophosphate pesticides,as the template, methacrylic acid as the functional monomer, and ethylene glycoldimethacrylate as the cross-linker. The adsorption capacities of the prepared imprintedpolymer toward eight organophosphate pesticides （dichlorvos, methamidophos, acephate,folimat, monocrotophos, parathion-methyl, phosphamidon, and malathion） were evaluated,and its potential as sorbent for solid-phase extraction was investigated. A novel method forthe simultaneous determination of multiple organophosphate pesticides residues in vegetableswas developed by utilizing molecularly imprinted solid-phase extraction coupled to gaschromatography. Under optimal solid-phase extraction conditions, with a flow rate of2.5mL·min^-1for loading100mL, the enrichment factor was in the range of25-480for the8organophosphate pesticides. The peak area precision （RSD） of the8organophosphatepesticides based on five replicates was from1.50%to4.09%. The accuracy of the proposedmethod was evaluated by recovery measurements on spiked cucumber samples, and goodrecovery rates ranging from80.11%to97.70%were achieved. Moreover, this method wasevaluated for the quantitative detection of multiple organophosphate pesticides residues inleek and pakchoi samples which were randomly purchased from the market.