A Study On Application Of Carbon Nanotube Modified Electrodein Analytical Chemistry

A Study on Application of Carbon Nanotube ModifiedElectrode in Analytical ChemistryThe article introduced the structure, properties and applied value of carbon nanotubes, especially emphasized on its application in analytical chemistry. Based on this, we carried out the following research work:1. Carbon nanotube was purified and dispersed in water, then as the modified material, it was dipped on the glassy carbon electrode to prepare chemical modified electrode. The electrochemical behavior of xanthine was studied by cyclic voltmmetry. Compared to the bare electrode, the anodic peak current increased greatly and can be used to determine xanthine. Xanthine was accumulated on the electrode surface at -0.6V potential and determined by stripping method after 15s quiet time. The stripping peak current is proportional to the concentration of Xanthine over the range 2.0×10-7～2.0×10-5 mol/L with 1-minutes accumulation. The detection limit is 2.0×10-8mol/L. The method has been successfully applied to the determination of xanthine in human serum.2. Carbon nanotube was modified on the surface of the glassy carbon electrode (GC)and first applied in the semi-derivative anode stripping voltammetry for the determination of 6-benzylaminopurine. The experiments suggested that the presence of carbon nanotube greatly increased the current of the oxidation peak of the benzylaminopurine. Cyclic voltammetry (CV) and semi-derivative voltammetry were used in a comparative investigation into the electrochemical oxidation of benzylaminopurine at the modified electrode. Studies on the effect of pH on the peak current and peak potential were carried out over the pH range 9.0～13.0 with the NH3-NH4Cl buffer solution. A pH of 10.0 was chosen as the optimum pH. Other experimental parameters, such as film thickness, accumulation potential, temperature etc were optimized. Anodic peak current was found to be linearly related to theconcentration of benzylaminopurine over the range of 4.0×10-8～1.0×10-5mol·L-1 with a detection limit of 5.0×10-10mol·L-1 in a 5min accumulation time. The method was used to determine sample and the results fit better to the result obtained with UV method. This method has the advantages of high sensitivity, better selectivity, better repeatability and strong ability to interfere. 3. A simple, inexpensive method for determining nitrite was presented. With carbon nanotube modified glassy carbon electrode (GC), the overpotential for reduction of nitrite decreased and the direct reduction could be achieved in acid solution, but the sensitivity is not very high. When cupric ion was added to the solution, the reduction peak current increased greatly and in particular, the presence of multiple nitrate did not interfere. The experimental condition was optimized and the electrochemical mechanism of nitrite reduction with the presence of cupric on the carbon nanotube modified electrode was preliminary studied. Under the optimized conditions, the peak current of reduction with differential pulse voltammetric method was proportional to the concentration of nitrite in two ranges: 2.0×10-6～1.0×10-5mol/L and 2.0×10-5～1.0×10-3mol/L, the detection limit could reach 5.0×10-7 mol/L and most of the inorganic ions did not interfere, the determinations of nitrite in samples of rain water and river water were satisfactory.