Abstract: The electrocatalytic characteristics of osmium complex polymer [Os(bpy)₂(PVI)₁₀Cl]Cl· (Os-PVI₁₀) and Nafion dual-layer membrane modified glassy carbon electrodes were studied. The modified electrodes show an excellent electrocatalytical activity for the oxidation of epinephrine(EP). Under the normal physiological condition, the catalytic current of EPvs. its concentration has a good linear relation in the range of 1.0×10^-6-8.4×10^-5mol/Lwith the correlation coefficient of 0.9987. Nafion membrane makes the modified electrodes eliminate efficiently the interference of ascorbic acid(AA). The modified electrodes exhibited a good reproducibility, sensitivity, and stability. The amperometric determination of EPconcentration can be performed at +250 mV. The kinetic research was performed with a rotating disk electrode, and the electrocatalytical rate constant k_ch was evaluated to be 3.53×10³mol^-1·L·s^-1. At a high EPconcentration, the relationship between the catalytic current and its concentration exhibits a Michaelis-Menten kinetic mechanism for the electrocatalytical process, and the constant K_m is about 147 mmol/L.

Key words: Chemically modified electrodes, Glassy carbon electrodes, [Os(bpy)₂(PVI)₁₀Cl], Nafion, Electrocatalytic oxidation, Biosensor