▎ 摘　　要

A methyl parathion electrochemical sensor based on nano-TiO2 and graphene composite film modified glassy carbon electrode has been developed. The electrochemical behavior of MP at the sensor was investigated by cyclic voltammetry and linear sweep voltammetry. Scanning electron microscopy was used to characterize the surface morphology of nano-TiO2 and graphene composite film. Compared with a bare glassy carbon electrode or a mono-film modified electrode, the redox peak currents of methyl parathion on the composite film modified electrode improved greatly, indicating that the sensor showed good catalytic effects. The optimal experimental condition was obtained. The results indicated that the linear sweep voltammetry responses of methyl parathion, in pH 5.2 acetate buffer solution with open-circuit accumulation for 2 min, were linear with concentrations of methyl parathion in two ranges of 0.002 similar to 5 mu M and 5 similar to 100 mu M. The linear equations were i(Pc)(mu A) = 0.0136 + 4.965c(MP)(mu M) (R-1(2) = 0.9911) and i(Pc)(mA) = 21.87 + 0.8206c(MP)(mu M) (R-2(2) = 0.9914), respectively. The detection limit was 1.0 nM (S/N = 3). The sensor exhibited high sensitivity and good reproducibility as well as certain anti-interference ability. It was applied to the determination of residual MP in fresh apple sample with the recovery of 92%similar to 102%. The result was satisfactory.