Study And Application Of Polarogrophic Catalytic Wave Of Antibiotic

The actions of organic drugs are very complex in the biochemical process, and they probably take part in the action of complexation or redox with proteins, reactive oxygen species and other substances. Therefore, the quantitative determination of organic drugs is an important factor of diagnosing illnesses and checking the curative effect in the clinical assay. Electroanalytical chemistry is one of the useful tools for the study of organic drugs, because of its obvious advantages in identifying the effective compositions, studying the metabolism kinetics and analyzing the clinical mechanism and effect of drugs. The polarographic wave of organic drugs mainly includes the reduction wave, the parallel catalytic wave and the catalytic hydrogen wave. Recently, the polarographic catalytic wave of organic drugs has been developed greatly, and plays an important role in improving analytical sensitivity, studying the kinetics of electrode process and free-radical chemistry, so it is an important branch of electroanalytical chemistry. Research on the polarographic catalytic wave of organic drugs may provide theoretical and practical basis for biomedicine, and has a significant effect on broadening the application range of electroanalytical chemistry.Based on the study of polarographic catalytic wave, it was observed that the catalytic hydrogen wave could be further catalyzed to produce a parallel catalytic hydrogen wave by oxidant KIO3, K2S2O8 or H2O2, which caused the peak current to increase obviously. In this thesis, the antibiotic drugs that contained the tertiary amine groups in their molecular structures, including midecamycin, lincomycin, tropicamide and erythromycin, were chosen as the research subjects. The characters and elctrode reduction processes of their catalytic hydrogen waves were investigated, and the corresponding parallel catalytic hydrogen waves in the presence of suitable oxidants were observed. The production mechanisms of these parallel catalytic hydrogen waves were elucidated, and the analytical methods with higher sensitivity were established. For studying the reaction kinetics of atomic hydrogen and the interaction of medicines with reactive oxygen species, the parallel catalytic hydrogen wave also provided a relatively simple method.This thesis consists of five parts:PART ONEAchievement of polarographic catalytic hydrogen wave of organic compounds. PART TWOA new type of polarographic catalytic wave of organic compound, termed as association / parallel catalytic hydrogen wave, has been reported. The association / parallel catalytic hydrogen wave with such characters as the negative shift of the peak potential and the great increase of the peak current in midecamycin - hydrogen peroxide system was studied. Here hydrogen peroxide as ligand formed an association complex with protonated midecamycin, which caused the peak potential of the catalytic hydrogen wave of midecamycin to shift negatively. Additionally, the great increase of the peak current resulted from the further catalysis of the catalytic hydrogen wave by hydroxyl radical produced in the reduction of hydrogen peroxide at electrode. In 0.15 mol-L-1 KH2PO4-NaOH (pH 7.4)-0.02 mol-L-1 H2O2 supporting electrolyte, the association / parallel catalytic hydrogen wave with peak potential -1.59 V (vs. SCE) in midecamycin - hydrogen peroxide system was two orders in magnitude higher than that of the corresponding catalytic hydrogen wave in analytical sensitivity. It was determined that the association ratio was 1:1 and the apparent association constant was 7.18. Moreover, the results studied in this work provided a relatively simple method for studying the interaction of medicines with reactive oxygen species, and additional evidence for explaining the procreant reasons of the side effect of midecamycin.PART THREEThe polarographic currents of lincomycin in the absence and the presence of persulfate were studied by linear potential scan polarography and cyclic voltammetry. The reduction wave of lincomycin in phosphate buffer was a c...