Electrochemical Preparation Of New Conducting Composite And Electrochemical Analysis Of Medicine

This paper involves two parts: Part one Documents ReviewThis review briefly describes the various aspects of conductive polymers, viz. synthesis, doping, classification, character and application, characterization of the properties. In addition, the polarographic analysis and the voltammetric analysis of medicine are shown in this review.Part two Research reportsThe two aspects are mainly performed in this thesis. On the one hand, the study on the synthesis of new conducting composite. The graft of electrodeposited polyaniline film by subsequent electrodeposition of L-cysteine leads to a new conducting composite, polyaniline/L-cysteine. Cyclic voltammograms, Fourier transform IR diffuse reflectance spectroscopy (FTIR-DRS) and scan electron microscopy (SEM) are used for the characterization of this composite. On the other hand, the study on the medical analysis. Calcium dobesilate is chosen as research subject. Its voltammetric behavior at a pencil graphite electrode is investigated and the square-wave voltammetry is applied to the determination of calcium dobesilate in pharmaceutical formulations. Finasteride is chosen as the other research subject. Its voltammetric behavior at a mercuric electrode is investigated and the determination of finasteride is performed by single-sweep oscillopolarography. In additional, the polarographic method for determination of 2-perfluoroheptyl-N-aminoethylimidazoline is established on mercury electrode.The concrete contents and results are described as follows: Chapter one Electrosynthesis and characterization of conducting composite,Polyaniline/L-cysteineA new electrically conducting composite, polyaniline/L-cysteine (PAn/L-Cys), has been synthesized on polyaniline (PAn) film electrode by electrochemical treatment. The conducting composite is characterized by cyclic voltammetry, FTIR-DRS and SEM. The result shows that L-cysteine (L-Cys) moves in PAn film during the electrochemical treatment process, and the radical cation of imino-l,4-phenylene, the intermediate of PAn, is preferentially stabilized by sulfhydryl group of L-Cys. PAn/L-Cys, a three-electron composite, is obtained. It is presumed that the conduction of PAn/L-Cys is better. Chapter two Voltammetric behavior and square-wave voltammetric determination of calcium dobesilate at a pencil graphite electrodeThe voltammetric behavior of calcium dobesilate (CDB) at a pencil graphite electrode (PGE) is investigated by cyclic and square-wave voltammetry in 0.2 mol L"1 BR buffer (pH 1.98). One pair of well-defined reversible redox peaks are observed at 0.63 V (vs. SCE) and one adsorptive anodic peak is observed at 1.23 V (vs. SCE). The anodic peaks correspond to a one-electron oxidation of the hydroxyl group of the phenol group, and the cathodic peaks correspond to a one-electron reduction of its free radical. Based on the anodic peak at 0.63 V in 0.2 mol L"1 BR buffer (pH 1.98), a square-wave voltammetric method is proposed for the determination of CDB. A linear relationship is obtained from 2.0xl0~4 to 6.5X10"4 mol L1, with the detection limit 1.8xlO"5 mol L1. The proposed method is applied to the determination of CDB in pharmaceutical formulations. Chapter three Determination of finasteride by single-sweep oscillopolarographyIn 0.01 mol L"1 HCl-2.5xlO"5 mol L"1 dodecyltrimethyl ammonium chloride-16% (v/v) ethanol base solution, finasteride yields a sensitive reduction wave with peak potential -1.27 V (vs. SCE). The second-order derivative peak current of the reduction wave is proportional to finasteride concentration in the range of 1.0 ~ 10.0 jxg mL"1, with the detection limit 0.2 ^g mL1. The proposed method can be applied to the determination of finasteride in tablets.Chapter four Polarographic determination of 2-perfluoroheptyl-N-aminoethyl-imidazolineIn 0.2 mol L"1 NH4Cl-0.2 mol L1 NH3H2O (pH 11.0) supporting electrolyte, 2-perfluo-roheptyl-N-aminoethylimidazoline (PHAEI) yieldes a catalytic hydrogen wave with peak potential -1.27 V (vs. SCE). The second-order derivative peak current of the catalytic hydrogen wave is proportional to the PHAEI concentration in the range of 0.02 ~ 0.11 g L"1, with the detection limit 0.004 g L"1. The proposed method is applied to directly determine PHAEI in industrial produce without pre-separation.