Poly (3-(3-Pyridyl) Acrylic Acid) Modified Glassy Carbon Electrode for Simultaneous Determination of Dopamine, Ascorbic Acid and Uric Acid

Electrochemical copolymerization of acrylic acid and acrylamide on the carbon fiber surface

Electrochemical polymerization of acrylic acid and acrylamide on carbon fiber was carried out by using cyclic voltammogram in the presence of sulfuric acid (H2SO4) as electrolyte. Cycles, monomer mass ratio, scan rate, and H2SO4 concentration had an effect on the electropolymerization, and electrochemical impedance spectroscopic behavior of modified carbon fiber was studied. Systematic experiments were conducted to determine the tensile strength of carbon fiber/epoxy resin composites before and after modification. As a result, the tensile strength of modified carbon fiber/epoxy resin composites was improved greatly. Surface morphology of the polymer films on carbon fiber was investigated by using scanning electron microscopy. It was found that voltammograms of electrodes prepared showed irreversible oxidation–reduction of the polymer films and capacitive behaviors of coated carbon fiber were defined using Nyquist plots, Bode magnitude plot and Bode phase plot at low-frequency region.

Simultaneous voltammetric determination of norepinephrine, ascorbic acid and uric acid on polycalconcarboxylic acid modified glassy carbon electrode

A novel polycalconcarboxylic acid (CCA) modified glassy carbon electrode (GCE) was fabricated by electropolymerization and then successfully used to simultaneously determine ascorbic acid (AA), norepinephrine (NE) and uric acid (UA). The characterization of electrochemically synthesized Poly-CCA film was investigated by atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS) and voltammetric methods. It was found that the electrochemical behavior of the polymer-modified electrode depended on film thickness, i.e., the electropylmyerization time. Based on the electrochemical data, the charge transfer coefficient (alpha) and the surface coverage (Gamma) were calculated. This poly-CCA modified GCE could reduce the overpotential of ascorbic acid (AA), norepinephrine (NE) and uric acid (UA) oxidation in phosphate buffer solution (pH 6.0), while it increases the peak current significantly. The current peak separations of AA/NE, NE/UA and AA/UA on this modified electrode are 91mV, 256mV and 390mV in CV at 100mVs(-1), respectively. Therefore, the voltammetric responses of these three compounds can be well resolved on the polymer-modified electrode, and simultaneously determination of these three compounds can be achieved. In addition, this modified electrode can be successfully applied to determine AA and NE in injection and UA in urine samples without interferences.