Study On Method For Fast Detection Methamidophos Based On CdSe/ZnS Quantum Dots And Molecular Imprinting Technique

As a highly toxic pesticide,MAP has been prohibited since 2008.However,recent detection and regulation of pesticide residues showed that the MAP is still existed in food.Thus development a quick and easy method to detect MAP is also indispensable.Traditional detection methods are generally chromatography.Although with the high accuracy and sensitivity,in practice,they require expensive equipments,time-consuming experiments,high testing cost,complex pre-processing,specialized personnel and other operating conditions which limit their wide application.In this study,a method for rapid detection of pesticide MAP in fruits and vegetables has established combined molecular imprinting technique with fluorescence quenching technique.The main results are as follows:(1)The MAP-molecularly imprinted polymer was fabricated and the ratio among template molecule,cross-linking agent and functional monomer was optimized.It was characterized by Infrared spectroscopy,adsorption kinetics and equilibrium binding assays.(2)The QDs-MAP molecularly imprinted polymer was synthesized using CdSe/ZnS quantum dots as core,methacrylic acid as functional monomer,ethylene glycol dimethacrylate as a cross-linking agent,and azobisisobutyronitrile as initiator by bulk polymerization.(3)Optimize the treatment conditions of MAP detection.Experimental results showed that after a reaction time of 3 h,the differential of fluorescence intensity was maximum.When the adsorbent was ultra-pure water,the fluorescence of MIP had greatest difference in compared with NIP.And polymers had good fluorescence stability.The imprinted factor of synthetic polymer was 4.413.(4)Establish of a new method for rapid MAP detection.Under optimal conditions,the linear range was 3.5× 10-7-0.71× 10-3 mol L-1,and the limit of detection was 9.164 × 10-8 mol L-1.The RSD for 8 replicate measurements of 4.0 × 10-4 mol L-1 MAP was 4.1%.Selective experiments toward the acephate,monocrotophos,trichlorfon and other structural analogs were conducted,and results demonstrated that the imprinted polymers had good recognition toward MAP.This method was applied for detection of actual sample including kidney beans,leek and cucumber.Compared with the result of gas chromatography method,there was no significant difference between the two method.