New Methods For Determination Of Trichlorfon Based On Molecularly Imprinted Technology

Trichlorfon is a broad-spectrum organophosphorus pesticide, which has characteristicssuch as high efficiency, low toxicity, low-residue and good water solubility. It has beenwidely used in agriculture, forestry, horticulture, animal husbandry, health, etc. Buttrichlorfon is also a cholinesterase inhibitor, mutagenic and teratogenic agents, and thebiological and environmental hazards caused by its residues have gained more and more closeattention of the people and researchers. Therefore, development of a sensitive and effectiveseparation and analysis method for trichlorfon is required and of great importance.Two novel methods based on the molecularly imprinted technology for the rapid andeffective determination of trichlorfon residues in vegetables were founded in this research.1. An online molecularly imprinted solid phase extraction coupled to chemiluminescencesensor for the determination of trichlorfon.In this method, the molecularly imprinted polymer （MIP） was prepared through bulkpolymerization, in which methacrylic acid （MAA） was used as the functional monomer andethylene glycol dimethacrylate （EGDMA） as the cross-linker. This novel functionalizedmaterial was characterized by FT-IR spectra and adsorption, and it exhibited good recognitionand selective ability and fast adsorption desorption dynamics toward trichlorfon. Using theMIP as a sorbent, an online molecularly imprinted solid phase extraction coupled tochemiluminescence sensor （MISPE-CL） method was founded. The factors affectingpreconcentration of the analytes and sensitivity of the method are discussed in detail. Underthe optimal condition, the linear range of the calibration graph was between0.02and1.0ng/L,and the detection limit was1×10³ng/L. The blank cucumber samples spiked with trichlorfonat three levels were extracted and determined by the presented method with recoveriesranging from83.5to94.5%, and the results were correlated well with those obtained usinggas chromatography. Moreover, this developed method was applied to the quantitativedetection of trichlorfon residues in leek samples. 2. A direct competitive biomimetic enzyme-linked immunosorbent assay based on ahydrophilic molecularly imprinted membrane for the determination of trichlorfon.In this study, a sensitive direct competitive biomimetic enzyme-linked immunosorbentassay （BELISA） method was developed for the determination of trichlorfon based on ahydrophilic imprinted membrane, which was directly synthesized on the well surface ofMaxiSorp polystyrene96-well plate through bulk polymerization technology. This novelimprinted membrane was characterized with high binding ability and specificity. Under theoptimal conditions, the sensitivity （IC50, half maximal inhibitory concentration） and the limitof detection (LOD, IC₁₅) of this method were6800±60μg/L and6.8±0.20μg/L, respectively.This BELISA method had been applied to the determination of trichlorfon with goodrecoveries ranging from106.0to110.5%, and the results were correlated with that obtainedby the gas chromatography method. Moreover, this method was applied to quantitativedetection of trichlorfon residues in the leek samples. The method developed in this study issensitive, stable and simple. Without antibody coating and blocking procedure, the operationtime was reduced. Furthermore, the cost per analysis of this new method was drasticallyreduced, and it was more suitable as a tool for the rapid detection of trichlorfon.