Studies On The Characterization Of Nafion Modified Glassy Carbon Electrode And Its Analytical Applications

Recently, chemically modified electrodes (CMEs) have been given highly investigations in the fields of electrochemistry and electroanalytical chemistry. Through various methods such as covalence, adsorption, polymerization, some specific electrocatalytic substances are modified onto the surface of the naked electrodes to fabricate the CMEs which make the electrochemical reactions to the desired directions. The CMEs have so many advantages including high sensitivity, relative simplicity and low cost of equipment that they are dramatically applied to the analytical detections.The Nafion polymer is chemically inert, noneletroactive, hydrophilic and insoluble in water and thus possesses almost ideal properties for preparation of modified electrodes. The CME tends to exclude anionic and neutral interferences .On the basis of previous study, Nafion modified glassy carbon electrode was fabricated used for determination of trace indium and tin in the water samples by the adsorption stripping voltammetry (ASV) .Besides, a novel multi-walled carbon nanotubes (MWNTs)- Nafion modified glassy carbon electrode was also fabricated for the A method for determination of L-Dopa which is one of the most important catecholamines. The main researches were summarized as follows:1. A Nafion modified glassy carbon electrode (NMGCE) is fabricated, and its advantages were given intensive studies.2. A new method for determination of trace indium is proposed by the adsorption stripping voltammetry (ASV) using a Nafion modified glassy carbon electrode. This chemically modified electrode (CME) shows a better stability. A sensitive oxidation peak was observed and the anodic peak potential is ca.-0.548V (vs. SCE). The influences of various experimental parameters on the current peak were completely studied. Under the optimized condition, the method has been applied to the determination of indium in water samples. There is a good linear relationship between the peak current (i_p) and indium (â…¢) concentration in the range of 1.0×10^-91.0×10^-7mol/L and the limit of detection is 7.5×10^-10 mol/L.3. An application of using a Nafion modified glassy carbon electrode to detect trace tin by Voltammetry is reported. The experimental conditions have been optimized. Thepeak current is proportional to the concentration of tin in the range of lxlO"9 ^lxlO"7mol/L, and the limit of detection is 2.46xlO"10 mol/L. The method has been applied to the determination of tin in water samples and the average recovery is 97.24%.4. A method for determination of L-Dopa is proposed by the adsorption stripping voltammetry (ASV) using a multi-walled carbon nanotubes (MWNTs)- Nafion modified glassy carbon electrode (GMGCE). This chemically modified electrode (CME) shows a better stability. A sensitive oxidation peak was observed and the anodic peak potential is ca.0.374V (vs. SCE). The influences of various experimental parameters on the current peak were completely studied. Under the optimized condition, the method has been applied to the determination of L-dopa in samples. There is a good linear relationship between the peak current (ip) and L-dopa concentration in the range of 3.5xlO"7 ¹.5xlO"5 mol/L* with the limit of detection is 5.0xl0"8 mol/L,...