Studies On The Adsorption Voltammetric And Adsorption Catalytic Voltammetry Of Organic Drugs(Nifedipine,Indirubin Et Al.)

In this paper, a new kind of adsorptive catalytic voltammetry at carbon paste electrode (CPE) in the presence of dissolved oxygen was developed. The voltammetric behavior of organic drugs (Nifedipine, Indirubin, Rhein, Hesperidin,Isatin) was studied by the proposed method. Adsorptive catalytic voltammetry plays an important role in both improving analysis sensitivity and studying kinetic of electrode process. A new approach was provided for determination of organic pharmacy by electrochemical analysis.The dissertation consists of six chapters.In the chapter one, poloragraphic catalytic wave of organic medicine especially bioactive material was summarized. Application of adsorptive voltammetry in trace analysis of organic medicine, advantage of carbon paste electrode in biosensors and electroanalytical chemistry method of determination of DNA were elaborated. Moreover, application of adsorptive catalytic voltammetry of some medicines was introduced.In the chapter two, a novel adsorptive voltammetry for the determination of nifedipine (NIF) at carbon paste electrode (CPE) was described. The voltammetric behavior of NIF on a CPE was explored by linear scan voltammetry, cyclic voltammetry, ultraviolet spectrophotometry and constant potential electrolysis. The experiment results indicated that nitryl in NIF was reduced irreversibly to hydroxyamino at CPE, and a well-defined peak was obtained at–0.77V(vs. SCE) in borate buffer (pH 9.7). Under the optimization of pH, concentration and scan rate, the second-order derivative peak current was proportional to the nifedipine concentration in the range of 4.0×10^-9～2.9×10^-7 mol/L (accumulation 60 s). The limit of detection was 1.2×10^-10mol/L (S/N=3) for a 90 s accumulation time. The method has applied to the determination of trace nifedipine in the urine samples with satisfactory results.In the chapter three, a novel sensitive adsorptive catalytic voltammetry for the determination of indirubin at CPE was developed. In K₂HPO₄-NaH₂PO₄ (pH8.5) buffer solution, indirubin was efficiently accumulated at a CPE by adsorption, and reduced to a intermediate free radical in the course of potential scanning. In the presence of K2S208, intermediate free radical was oxidized, and diindyl structure was regenerated, thus yielding a sensitive parallel catalytic voltammetric peak at -0.6V (vs. SCE). The second-order derivative peak current was proportional to the indirubin concentration in the range of 1.9×10^-9～3.8×10^-8 mol/L (accumulation 90s) and 3.8×10^-8～1.9×10^-6 mol/L (accumulation 60s), the coefficient correlation are 0.9979 and 0.9986, the limit of detection was 6.0×10^-10 mol/L (S/N=3). The electrode reaction mechanism of indirubin...