The Preparation And Its Application Of Carbon Nanotube And Polymer Chemically Modified Electrodes

Chemically modified electrodes have been active in the forefront ofelectrochemistry and electroanalytical chemistry field. The modified material plays animportant role in this field. As always, it has attracted more and more attention.MWCNTs and amino acid polymer have gotten extensive application byelectrochemical workers depending on their own unique properties. The MWCNTspossesses the advantage of good electric conductivity, large surface area,electrocatalytic performance and good chemical stability. Based on sensorapplications, it could produce specific catalytic effect to the electrochemical behaviorof analytes. Polymer film also has attracted lots of attention with a series of meritssuch as simple preparation, long service life, diverse methods, strong connectionbetween membrane and the base electrode. In view of this background, the MWCNTsand polyaminoacid material were used as the main modifier in this thesis. Based onthis, three kind of voltammetric sensors were fabricated and used for sensitive andfast determination of some useful small molecule materials. The main research areexpressed as follows:1. A simple and reliable electrochemical sensor based on poly(DL-Aspartic acid)modified glassy carbon electrode was proposed for direct determination of brucine.The electrochemical characters of brucine on this sensor was carefully andsystematically studied by cyclic voltammetry. Some kinetics parameters werecalculated and a reasonable reaction mechanism of brucine at the poly(DL-Asparticacid)/GCE was also proposed. Meanwhile, a new electroanalytical method fordetermination of brucine was proposed with highly sensitive detection limit of3×10-8mol L-1(S/N=3) and wide linear range of5.0×10-8mol L-1to9.0×10-5mol L-1.2. A sensitive, fast and cheap voltammetric sensor for quantitative determinationof synephrine in Chinese traditional herbal drug pericarpium citri reticulatae usingglassy carbon electrode (GCE) based on MWCNTs-Nafion film was reported. Theelectrochemical behavior of synephrine on this sensor was explored inBritton-Robinson buffer solution using cyclic voltammetric technique. Moreover, cyclic voltammetric studies indicated that the oxidation of synephrine at the modifiedelectrode was irreversible, adsorption controlled and involved two electrons. Linearcalibration plot between the oxidation peak current and the synephrine concentrationwas in the range of1×10-8to1×10-5mol L-1. Detection limit of synephrine was foundto be8×10-9mol L-1by linear sweep voltammetry technique. Besides, the analyticalperformance of this sensor was evaluated for the detection of synephrine in realsamples.3. A new voltammetric sensor, based on multi-walled carbon nanotubes(MWCNTs) composite poly(aspartic acid) film modified glassy carbon electrode, wasfabricated and used for determination of pesticide imidacloprid. The synergistic effectof MWCNTs and the polymer resulted in a significantly improved electrochemicalresponse of imidacloprid. Under selective conditions, the detect linear range was from6.0×10-8mol L-1upto6.0×10-5mol L-1with a detection limit of4.5×10-8mol L-1. Thesensor also had an easily renewable surface, good fabrication reproducibility, andinherent stability. Moreover, satisfactory results were obtained with complexenvironmental samples and demonstrate the reliability of the method.