Electro-separation Of Dopamine, Uric Acid And Ascorbic Acid Based On A Graphite Electrode Modified Polyaniline

Polyaniline (PAn) has attracted considerable interesting due to its availability, simple synthesis, high conductivity and stability. Because Polyaniline film has a unique doping behavior and good electrochemical reversibility,a lot of research of PAn-film modified eleetrode in the analysis and testing has been conducted. Dopamine (DA),uric acid (UA),ascorbic acid (AA) are small molecules of life that present in the body,it is significant to analysis these three substances, the electrochemical detection of three mixed systems has also been one of the hot. In this paper, a polyaniline modified graphite electrodes was prepared by cyelic voltammetry, the peak potential of dopamine,uric acid and ascorbic acid were separate on the modified electrode, and can achieve simultaneous detection of three components.This paper mainly carried out the following two aspects:1. A new electrode of polyaniline modified graphite was prepared by electrochemical deposition, several factors affecting the polymerization of aniline on the electrode surface have been investigated. the experimental results showed that the best polymerization conditions are: the upper scanning potential of cyclic voltammetry is 0.95 V, the lower scanning potential is -0.2 V, the concentration of aniline is 0.020 mol/L, the scan weeks are 20, scanning rate is 0.05 V/s. Different PAn films were obtained by varying the experimental parameters, characterized them by cyclic voltammetry, UV, scanning electron microscopy and discuss the reaction mechanism simplely. The modified electrode can be stable in the air.2. Determinating the mixed solution of dopamine, uric acid, ascorbic acid by PAn / SG modified electrode. In the solution of 0.5 mol/L vitriol,the peak potential of these there component were separated on the electrode, the potential difference between dopamine and uric acid is 110 mV, the potential difference between dopamine and ascorbic acid is 250 mV. Their peck current was linear respond to their concentration. The detection limits are as follows: DA is1.00×10^-5 mol/L,UA is 1.10×10^-5 mol/L,AA is 2.00×10^-5 mol/L. Discuss the reversible,adsorption,the electrons of transfered and the protons in the responses of three components by Cyclic voltammetry technique.