Study On The Methods For Determination Of Trichlorfon Based On Molecular Imprinting And Capillary Electrophoresis Technology

This study worked on the problem of organophosphorus pesticide residues in vegetables. Two new methods for fast detection of trace trichlorfon pesticide residues in vegetables had been developed in this study.1. MISPE-CE method for the determination of trichlorfon in vegetablesIn this study, we reported a new method of solid-phase extraction coupled to capillary electrophoresis (CE) based on a molecularly imprinted polymer (MIP) for the fast determination of trace trichlorfon. The electrophoretic conditions and factors affected the molecularly imprinted solid-phase extraction were optimized. Under the optimal conditions, the linear ranges of the calibration graph were0.1mg L-1to10mg L-1. The limit of detection (LOD) and method quantitation limit (MQL) were24.5μgkg-1and80.9μg kg-1respectively. With a flow rate of2.5mL min-1for loading100mL, an enrichment factor of160was obtained. The relative standard deviation (RSD) for five replicate extractions,0.01mg L-1trichlorfon standard solution was4.5%. The blank cucumber samples spiked with trichlorfon at three levels were extracted and determined by this presented method with recoveries ranging from75.2%to93.9%, and the results were in good agreement with that obtained by the gas chromatography method. Moreover, this proposed methodology was successfully applied to quantitatively detect of the trichlorfon residues in the leek samples.2. MICEC method for determination of trichlorfon in vegetablesA novel molecularly imprinted capillary monolithic column was prepared using trichlorfon as the template molecule by combining a molecular imprinting technique with a sol-gel process. The resulting materials were characterized by SEM and FTIR. Under capillary electrochromatography, the effects of different parameters on the electroosmotic flow (EOF) of the imprinted capillary monolithic column were investigated in detail. Using this prepared material as a stationary phase for the capillary electrochromatography, a novel method of molecularly imprinted capillary electrochromatography (MICEC) for the detection of trace trichlorfon residues in vegetables was developed. Under optimal conditions, appreciable sensitivity had been achieved with the limit of detection (LOD)(S/N=3) of92.5μgkg-1and method quantitation limit (MQL) of305.3μgkg-1, respectively. The linear ranges of the calibration graph were0.05mg L-1to10mg L-1. The peak area precision (RSD) for five replicate extractions of0.01mg L"1trichlorfon standard aqueous solution was4.5%. 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 from80.2%to95.8%. Moreover, this method was successfully applied to the quantitative detection of the trichlorfon residues in leek samples.