Studies And Applications Of Chemically Modified Active Carbon Paste Electrode

Chemically modified carbon paste electrode (CMCPE) is one of chemically modified electrodes (CMEs). The base of modified carbon paste is usually powdered graphite and nonelectrolytic binder. Another constituent is modifier itself. CMCPE has lots of advantageous characters that not only chemically modified electrode but also carbon paste electrode (CPE) has. As one of CMEs, CMCPE can be designed to process certain desired functions, and used for determination of corresponding substance. The rate of electron transfer is faster than common electrode on the surface of electrode. The high analytical sensitivity can be obtained due to the modifier. As one of CPE, CMCPE can offer many advantageous properties such as wider potential windows, rapid renewal of electrode surface, long performance life, high stability, good repeatability and reproducibility. In addition, it is inexpensive and can be fabricated easily. In our test, the active carbon powder we used was prepared by rice husk and was proved to have larger external surface and abundant surface functional groups such as carboxylic, lactonic groups and so on, which can adsorb many substances. To utilize all these specific properties, the active carbon powder was modified with some modifiers, then mixing the carbon paste with graphic and solid paraffin in the optimum rate. The new fabricated CMCPE was used for the determination of some inorganic ions or biologic substances. As we expected, the results were satisfying. The total test was consist of four chapters as follows: Chapter 1 introduced the origin, the theory, the measures of fabrication of CME, CPE and CMCPE. At the same time, it gives a bird's eye view of their application and development. Chapter 2 described the determination of dopamine using the active carbon modified carbon paste electrode (ACMCPE) by cyclic voltammetry and differential pulse voltammetry. Utilized the special quality of abundant surface functional groups, a well quasi-reversible redox peak appeared between 0.37V and 0.04V when ACMCPE was scanning in pH=7.63 phosphate buffer solution (PBS) containing dopamine at a scan rate of 100mV/s. There were three linear calibrate curves of DA in the concentration range of 2×10-7 M~1×10-3 M for different preconcentration time. The determination limit for Signal/Noise=3 was 7.5×10-8 mol/L. Ascorbic acid (AA) as the familiar interfering compound had a little interference in analysis procedure. Chapter 3 mainly concerned with the determination of Copper (Ⅱ) with active carbon paste electrode modified with sodium alizarinsulfonate by anodic stripping voltammetry. Through the compared test with the traditional fabricated measure of modified carbon paste electrode, the new electrode offered more stable and better repeatable and reproducible properties. The effect of some experimental parameters were studied, such as the best ratio of carbon paste, pH of supporting electrolyte, scan rate, preconcentration potential, preconcentration time and so on. The determination of Cu (Ⅱ) in...