Dispersed Platinum Polyaniline Modified Electrode Catalysis Of Electrooxidation Of Adrenaline

Epinephrine is an important catecholamine neurotransmitter in mammalian central nervous system, which plays a particularly important role in the biology action and nervous chemical processes in nervous system. So, electrochemical studies of epinephrine and analogies have an important role in biological samples. Polyaniline, one kind of conducting polymers, with porous strueture and high surface area, is usually used as matrix to incorporate Pt partieles to prepare Pt-modified Polyaniline ectrodes(Pt/PAn/GC). This paper proved that Pt-modified Polyaniline ectrode has a high efficieney in electrocatalytic activity of epinephrine and analyzed the factors that affect the prepare of Pt-modified Polyaniline ectrodes.In this paper, choosing EP probe, several factors affecting the electrocatalytic oxidation have been investigated. By using cyclic voltammetry, optimum condition for Pt deposited on the surface of polyaniline is estimated:the concentration of the acid medium HCl is 2.0 mol/L, the scanning rate is 50mV/s. The behaviors of epinephrine on this modified electrode was studied by cyclic voltammetry in the eight kinds of medium including pH=0.5 HCl solution, HClO4 solution, H3PO4 solution, HNO3 solution, H2SO4 solution, HCl and KCl buffer solution, HNO3 and KNO3 buffer solution, HClO4 and NaC104 solution, the Pt/PAn/GC electrode shows excellent electrocatalytic activity for oxidation of epinephrine. Compared to Polyaniline Modified electrode(PAn/GC) and Glassy carbon electrode (GCE), Pt/PAn/GC electrode has a better electrocatalytic behavior for EP. The relationship between v1/2 and ip of EP is liner, which indicate that the electron transfer process of EP is controlled by diffusion. In 1.5 mol/L HCl+1.5 mol/L KCl solution, the oxidation peak current was linear depending on the EP concentration between 9.0×10-6 mol/L～2.5×10-3 mol/L. The detection limit is 1.6×10-6 mol/L. It has been applied to the determination of EP in injection and human serum.The electrocatalytic activity of EP was studied by Electrochemical Impedance Spectroscopy at the Pt/PAn/GC electrode in HCl solution and HCl+KCl solution. The experimental results show that, with the increasing concentration of hydrochloric acid solution, the charge transfer resistance of the polyaniline membrane is getting smaller and smaller, and charge transfer accelerate; The electrocatalytic activity of EP was also studied by Electrochemical Impedance Spectroscopy at the Pt/PAn/GC electrode, PAn/GC electrode and Glassy carbon electrode in HCl +KCl solution ,the results indicate that the Glassy carbon electrode has a higher resistor in HCl +KCl solution compared to Pt/PAn/GC electrode and PAn/GC electrode, besides, the PAn/GC electrode has a higher resistor in HCl+KCl solution compared to Pt/PAn/GC electrode, the Pt/PAn/GC electrode has the ability to decrease the oxidation resistance of EP ,which is similar to that of by cyclic voltammetry.