Abstract: A parathion electrochemical sensor based on nano-Al₂O₃/graphene composite film modified electrode has been developed. Scanning electron microscopy（ SEM） was used to characterize the surface morphology of nano-Al₂O₃ film and nano-Al2O3/graphene composite film. The electrochemical behavior of parathion at the sensor was investigated by cyclic voltammetry（ CV） and linear sweep voltammetry（ LSV）.Compared with bare glassy carbon electrode， the sensor showed good catalysis for the redox of parathion due to porous structure of nano-Al2O3 and excellent conductivity of graphene. The optimized experimental conditions were obtained. The results indicated that the LSV responses of parathion were linear with concentrations in the range of 0. 05 to 60 μM with linear equation of i_pc（ μA） = 5. 666+0. 693 7 c（ μM）in pH 5. 2 acetate buffer with open circuit accumulation for 2.5 min. The detection limit was 20 nM（ S / N =3） and R =0. 996 4. The sensor exhibited high sensitivity and good selectivity as well as certain anti-interference ability. It was applied to the determination of residual parathion in fresh cabbage sample with the recovery of 94. 5%~101. 0%. The results were satisfactory.

Key words: graphene, nano-Al₂O₃, parathion, electrochemical sensor