Studies On The Adsorptive Voltammetry Of Tin(Ⅳ),Silver(Ⅰ) And Antimony(Ⅲ) At Chemically Modified Carbon Paste Electrodes

In this paper, four new adsorptive voltammetry of tin(IV), silver(I),antimony(III) at Alizarin violet and pyrogallol red modified carbon paste electrodes have been investigated. These electrodes were prepared by incorporating Alizarin violet or pyrogallol red directly into a carbon paste matrix .This paper consists of four chapters:In chapter one, the determination of tin(IV) at Alizarin violet modified carbon paste electrode by adsorptive anodic stripping voltammetry has been studied in detail. In acetate buffer solution (pH4.8), the tin(IV) was accumulated on the Alizarin violet modified carbon paste electrode surface by the formation of the complex in an open circuit, then the electrode system was transferred to 3.0mol/L HCl solution, and tin was determined by anodic stripping voltammetry after potential reduction at -0.80v(vs.SCE). The second order derivative peak potential is at about -0.68v. The concentration of tin(IV) is directly proportional to the peak current over the range from 8.4×10-9 to 1.4×10-6mol/L, the detection limit is 4×10-9mol/L for a 2min preconcentration time. The properties of stripping peak and the electrode processes mechanism have been studied by cyclic voltammetry. The method has been successfully applied to the determination of tin in cans food. In chapter 2, the adsorptive voltammetric procedure has been developed for the sensitive and selective determination of silver(I) at Alizarin violet modified carbon paste electrode. In acetate buffer solution (pH5.2), the electrode can accumulate silver(I) effectively at 0v. then the resulting electrode was introduced into 0.05mol/L sulfuric acid solution containing 2.0×10-5mol/LBr-. And the silver(I) was determined by anodic stripping voltammetry after potential reduction at -0.20v. The peak potential is at about 0.03v. The silver(I) concentration is proportional to the peak current over the range from 6.0×10-10 mol/L to 1.3×10-7mol/L, the detection limit is 2×10-10mol/L. The mechanism of electrode processes have been investigated, at the same time the enhancement mechanism of Br- has been studied in particular. The proposed method has been applied to the measurement of silver in zinc alloy.In chapter 3, the voltammetric behavior of antimony(III) at the Alizarin violet modified electrode has been investigated. The optimum experimental conditions were found to be the use of a 1.0% modifier loading, HCl-potassium-biphthalate buffer solution(pH2.4) as the accumulation medium, 0.6mol/L HCl solution as stripping medium, preconcentration time of 180s in an open circuit, the reduction potential of-0.60v, a reduction time of 25s, scan rate of 200mv/s at anodic scan mode. The peak potential is at about -0.05v. A well linear relationship between the peak current and the antimony concentration has been obtained in the range of 4.1×10-9~2.9×10-7 mol/L, the detection limit is 2×10-9mol/L. The electrode processes mechanism has been discussed by cyclic voltammetry. The proposed method has been applied to the determination of antimony in water sample with satisfactory results.In chapter 4, the pyrogallol red(PR) modified carbon paste electrode was prepared , and we have studied the voltammetric behavior of tin at the electrode surface. In acetate buffer solution (pH4.5), the tin(IV)was accumulated on the pyrogallol red modified carbon paste electrode surface by the formation of the complex of Sn(IV)-PR in an open circuit, then determined by anodic stripping voltammetry after potential reduction at -0.80v in 4.0mol/L HCl solution. The peak potential is at about -0.69v. The second order derivative peak current is linear with the Sn(IV) concentration over the range from 1.68×10-8 to 1.68 ×10-6mol/L, the detection limit is 8×10-9mol/L. The mechanism of electrode reaction has been studied by electrochemical techniques. This method has been applied to the determination of tin in cans food.In a word, we have prepared Alizarin violet and pyrogallol red modified carbon paste electrodes, and established several methods for...