Study On Novel Detection Methods For Organophosphorus Pesticide Residues Based On Capillary Electrophoresis Technology

This study worked on the problem of organophosphorus pesticide residues in vegetables and two methods for determination of organophosphorus pesticide residues in vegetables had been developed.1.Molecularly imprinted magnetic solid-phase extraction coupled with capillary electrophoresis(MIMSPE-CE)method for the determination of trichlorfon in vegetablesIn this study,a molecularly imprinted polymer(MIP)on the surface of Fe3O4@SiO2@CdTe(CdTe@MMIP)was synthesized using trichlorfon as template molecule,methacrylic acid(MAA)as the functional monomer,and ethylene glycol dimethacrylate(EGDMA)as the cross-linker.Using MIP as sorbent,a simple and quick method of MIMSPE-CE for determination of trace trichlorfon in vegetables was developed.Under optimal conditions,the limit of detection(LOD)of the method(S/N = 3)was 0.03 mg kg-1.The relative standard deviation(RSD)for five replicate extractions of 0.05 mg L-1 trichlorfon standard aqueous solution was 4.2%.To evaluate the accuracy of this method,the blank cucumber and cauliflower samples spiked with trichlorfon were extracted and analyzed by this method with good recoveries ranging from 82.0% to 96.6%.Moreover,this method was successfully applied to the quantitative detection of the trichlorfon residues in rape samples.2.The research of separation and simultaneous determination of acephate and isocarbophos using ionic liquidThe ionic liquids(ILs)and sodium dodecyl sulfate(SDS)were added as modifiers in the background electrolyte(BGE)for capillary electrophoresis to enhance the separation efficiency of acephate and isocarbophos.The separation conditions in terms of the the types of the IL,concentrations of the IL,SDS,and pH were optimized.The limit of detection of the method for acephate and isocarbophos was 0.154 mg kg-1 and 0.08 mg kg-1.The relative standard deviations(RSDs)of the peak areas and migration times were 1.9%-3.9% and0.4%-0.6%.To evaluate the accuracy of this method,the blank cucumber cauliflower,spinach and carrot samples spiked with acephate and isocarbophos were extracted and analyzed bythis method with good recoveries ranging from 76.8%-88.8%.