Electrochemical determination of methyl parathion using a molecularly imprinted polymer–ionic liquid–graphene composite film coated electrode

A molecularly imprinted polymer–ionic liquid–graphene composite film coated glassy carbon electrode (MIP–IL–EGN/GCE) was presented for the first time. It was fabricated by coating a GCE with IL-graphene oxide (GO) mixture, followed by MIP suspension. The resulting electrode was then conditioned at −1.3 V (vs SCE) in a Na2SO4 solution to make the GO turn to graphene (EGN). The MIP was prepared by free radical polymerization using methyl parathion (MP) as template, methacrylic acid as functional monomer, ethyleneglycol dimethacrylate as cross-linking reagent and 2,2′-azobis(isobutyronitrile) as initiator. The response property of MIP–IL–EGN/GCE to MP was studied. Under the optimized conditions, the peak current of MP was linear to its concentration in the range of 0.010–7.0 μM with a sensitivity of 12.5 μA/μM, and the detection limit was 6 nM (S/N = 3). When a 1.0 μM MP solution was determined for five times using a MIP–IL–EGN/GCE, the RSD of peak current was 2.3%; the electrode-to-electrode RSD was 6.4% (n = 5). The sensor also displayed high selectivity and stability. It was applied to the determination of MP in samples and the recovery was 97–110%.