| In all kinds of chemical modified electrodes, polymer film modified electrode has been an active and dominant domain in recent years because of its excellent properties such as high electroactive central concentration, long-term stability of the modifiers, easy modified means, good response to analyte, and easy to be observed. In this work, the fabrication and application of some polymer film modified electrodes in electroanalytical chemistry have been described.1. Electrochemical copolymerization of caffeic acid and aniline at the glassy carbon electrode and its electrochemical characteristicsThe electrochemical copolymerization of caffeic acid and aniline was carried out at a glassy carbon electrode by means of electropolymerization, and its electrocatalytic properties were investigated. The polymer obtained on the electrode showed good electrochemical activity and high stability even though in neutral and weakly basic media, which has developed the application of polyaniline. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in neutral medium on the modified electrode were also studied and the results showed that the response currents of AA, DA and UA in pH 7.0 phosphate buffer were greatly enhanced at this composite polymer electrode.2. Simultaneous voltammetric measurement of hydroquinone and catechol at a glassy carbon electrode modified with 4-aminobenzenesulfonic acidA poly (4-aminobenzenesulfonic acid) modified glassy carbon electrode was obtained in pH 7.5 phosphate buffer containing 4-aminobenzenesulfonic acid using electropolymerization. This modified electrode was easy to be fabricated with good stability and reproducibility. The voltammetric behavior of hydroquinone (HQ) and Catechol (CC) at the modified electrode was studied by cyclic voltammetry and different pulse voltammetry (DPV). The polymer film showed excellent electrocatalytic activity for the oxidation HQ and CC with activation overpotential. For the mixture containing HQ and CC, the two compounds could well separated each other with a potential difference of 130 mV, which was large enough to determine HQ and CC individually and simultaneously. The catalytic peak current obtained was linearly dependent on HQ and CC concentration in the range of 2.0×10-6to 3.0×10-4 mol l-1 and 2.0×10-6 to 3.0×10-4 mol 1-1 respectively. The detection limits for HQ and CC were 4.0×10-7 mol 1-1 and 4.2×10-7 mol 1-1 respectively. Under the optimum conditions, the electrochemical parameters have been determined.3. Simultaneous voltammetric measurement of dopamine and uric acid at a glassy carbon electrode modified with 4-aminobenzenesulfonic acid4-Aminobenzenesulfonic modified glassy carbon electrode was fabricated using electropolymerization. The electrochemical behavior of DA and UA on the modified electrode was investigated. It was found that the response currents of DA, and UA were greatly enhanced at this composite polymer electrode. The electrode exhibited a rapid response and a high sensitivity. The anodic peak current had a linear relationship with the concentration of DA and UA in the range of 1.0×10-5 to 1.9×10-4 mol 1-1 and 3.0×10-5 to 5.5×10-4 mol 1-1, respectively, and their detection limits were 4.0×10-7 and 2.2×10-6 mol 1-1, respectively. The electrode was applied to the determination of DA in injection with with satisfactory results.4. Simultaneous voltammetric measurement of hydroquinone and catechol at a glassy carbon electrode modified with caffeic acidA promising electrochemical biosensor was developed by electrodeposition of caffeic acid on a glassy carbon electrode. The electrochemical properties of the modified electrode were investigated, which showed stable and sensitive current responses toward the oxidation of hydroquinone (HQ) and catechol (CC). The sensor was also quite effective to simultaneously determine HQ and CC in a mixture. In pH 6.5 phosphate buffer, the linear response was obtained in the range of 1.6×10-5 to 3.4×10-4 mol 1-1 with a detection limit of 5.1×10-1 mol 1-1 for HQ, and 1.6×10-5 to 3.4×10-4 mol 1-1 with a detection limit of 5.0×10-7 mol 1-1 for CC, respectively.
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