OXIGRAPHによるO2以外の物質の定量分析について

Polarographic Measurements of Some Vitamins and Hydrogen Peroxide by Means of a Stationary Pt-Electrode

　微小白金電極を用いてpolarographicにO₂を定量することは，OXIGRAPH^6）11）等も製作されて可成り精度よく生体のO₂代謝の研究に応用される様になつている。一方O₂以外の種々の物質の定量にもまた広範囲な応用が期待される。

　水銀滴下電極とは異り，白金電極では電極面が常に更新されないので，金属等の分析では電解生成物が電極面に析出したりして定量分析には適しないと思われる。従つて電解生成物が水溶性であると予想される有機物の分析に本法の応用を試みた。

　The reduction and oxidation currents of vitamin B₁, C and hydrogen peroxide were mea-sured on a Pt-electrode by the use of an OXIGRAPH.

　It was found that vitamin C presented the reduction current besides the anodic current in KCl solution, though on an usual Hg-electrode no reduction current has hitherto been observed. The cathodic diffusion current were measured in the potential range of -0.5 to -0.8 volts and the anodic diffusion currents, in the range of +0.6 to+1.2 volts, both of which were linearly proportional to the concentration. The similar cathodic currents to that of vitamin C were observed also in vinamin B₁ solution and the fruit juices.

　The cathodic diffusion current of hydrogen peroxide was nearly half that of oxygen whereas both polarograms showed the same inflection. The anodic current of it, how-ever, showed no such simple diffusion current as the cathodic current, but a maximum at about +0.65 volts. And it was clarified the determination of hydrogen peroxide could be made by tne measurements of both cathodic and anodic currents.

　As ohe of the applications of the determination of hydrogen peroxide concentrations the reaction velocity of catalase was measured. The velocity constant thus obtained was 1.5 -2.3×10⁷/min. and nearly close upon the values observed previously by other methods.