Masanosuke Takagi

Polarography of α-Keto Acids in Aqueous and Nonaqueous Solutions

Phenylglyoxylic acid (I), phenylpyruvic acid (II), and pyruvic acid (III) were polarographically studied in buffer solutions and in DMF. Their reduction waves were reinvestigated in a wider pH range. Cyclic voltammetry showed that most electrode reactions of these acids in acidic pH are irreversible. pH-Dependence of E1⁄2 and limiting current was studied. The observed decrease of the limiting currents of II and III in the strongly alkaline region was attributed to the dissociation of their corresponding enol forms. The i-E curves of these acids in DMF showed successive poorly-defined reduction waves, while those of the corresponding tetraethylammonium salts (TEA salts) were found to be much simpler in shape. A small oxidation wave was also observed with TEA salts of II and III, suggesting the presence of the enol form in DMF. The reduction products of I and its salt in DMF were studied by means of controlled potential electrolysis and NMR-spectroscopy. The electrode reaction mechanism of α-keto acids in n...

386 - Polarographic studies on perfluorocarbon emulsion, hemoglobin and erythrocyte as oxygen carriers☆

Abstract The polarographic diffusion current of the O2 reduction was utilized to estimate the nature of O2 supply from O2 binding oxygen carriers. Perfluorocarbon (PFC) emulsion, hemoglobin (Hb) and erythrocyte were used as either artificial or natural oxygen carriers. The changes of O2 limiting current originated by the addition of an oxygen carrier into the electrolyte solution open or closed to the atmosphere under some restricted conditions were analyzed. It is concluded that the main rate-determining factor for O2 transport by PFC emulsion. Hb solution or erythrocyte suspension, may be attributed to the O2 diffusion inside the PFC particle, to the diffusion of O2 binding Hb in Hb solution, or to the diffusion of O2 binding Hb inside the erythrocyte, respectively.

Polarographic Evidence for the Reduction of Nitrite to Nitrogen Monoxide by Iron(II) Ions in Neutral Buffer Solutions and Characteristics of Cathodic Waves of Nitrogen Monoxide in the Presence of Iron Ions and Citrate

The reduction of NO2- to NO by Fe2+ in neutral buffer solutions containing excess citrate has been substantiated polarographically. Nitrogen monoxide exhibited three cathodic waves having a characteristic maximum in the presence of iron ions and citrate. The two waves ( E1/2s=-0.56 and -0.75 V vs SCE at pH 7) were of kinetic current, whereas the third wave(E=1/2=10V) having a maximum was a diffusion-controlled one. The NO concentration dependence of the limiting currents of the three waves showed a relation with the form of Langmuirs adsorption isotherm.