Investigation On Electrochemical Reduction Characters Of Carbonyl Compounds And Their Applications

Organic drugs investigated by electroanalytical methods are always an important field in analytical chemistry. For one thing, the electroanalytical techniques are characterized by simplicity, sensitivity," cost-effectiveness, precision, accuracy and speed. For another, the selectivity and sensitivity of analytical method can be further improved by investigating electrode process. And according to the appearance and disappearance of polarographic wave, we can deduce the generation of new product or decomposition of medicines. In addition, due to the existing resemblance between electrochemical and biological reactions we can assume that the reduction mechanisms taking place at the electrode and in the body share similar principles. In this thesis, organic drugs, especially some carbonyl compounds were studied systematically by several electroanalytical methods and the spectrum analysis. These studies may provide theoretical and practical basis for biomedicine, and have important significance in broadening the application range of the electroanalytical chemistry. This thesis consists of six chapters.1. The advance of electrochemical investigation of carbonyl compounds was reviewed with 105 references.2. In pH 2.09-9.07 Britton-Robinson (B-R) buffer solutions, the electrochemical behaviors of camptothecine (CPT) were studied by several electrochemical methods at a hanging mercury drop electrode, and a new method for the determination of CPT was established by normal pulse voltammetry. In different pH range of B-R buffer solutions, CPT could cause three reduction waves P₁, P₂ and P₃. Their reaction mechanisms were preliminarily presented. P₁ wave was a two-electron wave. P₂ wavewas a one-electron wave. P3 wave could be split into two waves P3a and P3b- P3a was a catalytic hydrogen wave, and P3b was further reduction of P2 wave with the property of adsorption. A linear relationship between the peak currents of Pi wave and the concentration of CPT was obtained in the range of 2.0x10'6².0xl0"5 molL"1. The determination limit was 8.0 X 10"7 mol-L"1.3. A detailed study of the polarographic reduction of methylhesperidine was presented. The methylhesperidine could yield three reduction waves in aqueous medium from pH 2.05 to 6.37. Pi wave was the absorptive frontal wave of P2. And P2 wave was an irreversible adsorptive wave of protonized MH involving one proton and one electron. P3 wave was also an irreversible adsorptive wave with one electron as the further reduction of P2 wave. And the peak currents of P3 wave were proportional to the concentration of methylhesperidine. In addition, its effect of eleminating superoxide anion radical caused by the auto-oxidation of pyrogallol was studied in pH 8.2 HCl-tris buffer solution. The results proved MH has antioxidant quality which is very efficient.4. The electrochemical behaviors of risperidone were studied in pH 7.07 10.32 B-R buffer solutions and 0.2 mol-L'1 NaOH solution by several electrochemical methods, and a new method for determination of risperidone in risperidone tablets was described. Risperidone yielded one wave P| as pH of B-R buffer solution was changed from 7.07 up to 10.07, which was a catalytic hydrogen wave. Additional two waves P2 and P3 were exhibited in pH 10.32 B-R buffer solution. P2 wave was an irreversible adsorption reduction wave involving one electron. P3 could be split into P3a and P3t,. Of them, P3a was the further reduction wave of P2, and P3b was a catalytic hydrogen wave. Otherwise, the first-order derivative peak current of Pi wave and the concentration of risperidone were proportional in the range of 1.6x10" ².0x10"6 mol-L". The determination limit was l.OxlO"6 mol-L"1.5. The polarographic behaviors of domperidone and its application were studied. In pH 8.05-10.92 NH3-NH4CI buffer solutions, domperidone could yield a reduction wave. The experiment showed that the electroactive centers of domperidone were the C=O bonds. The electrode reaction mechanism was preliminarily presented. In therange of S.OxlO^-l.OxlO"4 molL'1, the peak currents of domperidone were proportional to the concentration of domperidone. The method was used to determine domperidone.6. The electrochemical behaviors of ketoconazole in pH 3.25⁶.08 NaAc-HAc buffer solutions were studied at a hanging mercury drop electrode. And the mechanism of ketoconazole was preliminarily presented.