| Using phoxim as template,α-methacrylic aid(MAA) as monomer,ethylene glycol dimethacrylate(EDMA) as cross-linker and 2,2-azobisisobutyronitrile(AIBN) as initiator,the phoxim molecular imprinted polymers(MIPs) was synthesized by polymerization in acetonitrile.MIPs were characterized by infrared spectroscopy and scanning electron microscopy.Scatchard plot analysis revealed that two kinds of different binding sites existed in MIPs,in which the maximum amounts of apparent binding and dissociation constants of binding sites were as follows:Qmax1=70.58 μmol/g,KD1=0.72 mmol/L;Qmax2=531.8 μmol/g,KD2=7.80 mmol/L.5 mg polyvinyl chloride(PVC) and 15 mg imprinted polymer were ultrasonically dispersed in 20 mL of tetrahydrofuran(THF),phoxim molecularly imprinted polymer modified electrode was prepared by adding 32 μL the dispersion dropwise onto the surface of glassy carbon electrode(GCE).Linear sweep voltammetry(LSV) was employed in the process of electrochemical measurements.The experimental results showed that the optimum acidity of 0.03 mol/L HCl-0.02 mol/L KCl solution is pH 2.2,and the optimum incubation time is 5 min.A highly linear response to phoxim in the concentration of 1.2×10-7-6.0×10-3 mol ?L-1 was observed,with a detection limit of 60×10-8 mol/L estimated at a signal-noise ratio of 3.The sensor was applied in the analysis of phoxim in real sample with recoveries of 93.8%-96.2%.The electrode modified with phoxim molecular imprinted polymer exhibited a good selectivity and sensitivity to phoxim when it was exposed to a series of closely related compounds with similar electrochemical characteristics,e.g.triazophos,chlorpyrifos and dimethoate. |