Study On Detection Methods For Multi-organophosphorus Pesticide Residues Based On Molecular Imprinting Technology And Chromatography

The inappropriate and excessive use of organophosphorus pesticides also results in the problem of pesticide residues exceeding in plants, which is impacting the environment and people’s health seriously. Therefore, in addition to strengthening the management of pesticides, developing a simple, fast, sensitive and efficient detection method is necessary.In this study, two novel methods for the detection of multi-organophosphorus pesticides were established based on molecularly imprinting technology and chromatography. Details are as follows:1. Molecularly imprinted solid phase extraction-high performance liquid chromatography for the determination of three organophosphorus pesticides in vegetablesIn this part, a molecularly imprinted polymers(MIPs) was synthesized using a common template of organophosphorus pesticides, 4-(dimethoxyphosphorothioylamino)butanoic acid as the template. The new functionalized material was characterized by static adsorption experiment and kinetic adsorption experiment. It exhibited good recognition ability towards the three organophosphorus pesticides(dimethoate, isocarbophos, and methyl parathion).Using this compound as sorbent for solid-phase extraction, a new method for simultaneous determination of three organophosphorus pesticides was established. The factors affecting the preconcentration were studied in detail. At the optimal conditions, the limit of detection of this method for dimethoate, isocarbophos, and methyl parathion was 19.78 μg kg-1, 8.73 μg kg-1, and 17.41 μg kg-1, respectively. The relative standard deviation for five replicates was in the range of 1.8-4.2%. Cucumber sample spiked with the three organophosphorus pesticides were examined using this method, good recoveries were obtained ranging from 82.5 to 95.6 %.Moreover, this method was also successfully used for the detection of the three organophosphorus pesticides in cauliflower sample.2. A molecularly imprinted monolithic capillary electrochromatography method for the determination of acephate and phosphamidon residues in vegetablesIn this part, a molecularly imprinted capillary monolithic column was synthesized by an organic-inorganic hybrid method using a common template–4-(dimethoxyphosphorothioylamino)butanoic acid as the template, methacrylic acid as the functional monomer, and γ-methacryloxypropyltrimethoxysilane as the cross-linker.The resulting material was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy, the electroosmotic flow at different conditions was also measured. Using this prepared monolithic column as the stationary phase of capillary electrophoresis, a new method for simultaneous determination of the two pesticide residues was established. The limit of detection of the presented method was 90.3 μg kg-1 for acephate and 96.1 μg kg-1 for phosphamidon. The cucumber and lettuce samples spiked with acephate and phosphamidon were extracted and analyzed by this method with satisfactory recoveries ranging from 79.7% to 94.4%, and the relative standard deviation for three replicates was in the range of 1.5-4.6%. This method was successfully applied to quantitative detection of acephate and phosphamidon residues in leek sample.