含窒素官能基群を導入したカーボンフェルト電極を用いる次亜塩素酸のバッチインジェクションクーロメトリー

抄録

Nitrogen atoms containing functional groups, such as amino group, were introduced by the electro-oxidation of carbon felt electrode into an ammonium carbamate aqueous solution. We found that the reduction wave of hypochlorite could be well-separated from that of oxygen in the cyclic voltammogram obtained by using this electro-oxidized carbon felt electrode as a working electrode. This result means that the selective reduction wave of hypochlorite appears due to an electrochemical introduction of electrocatalytic active sites containing nitogen atoms. This activated carbon felt electrode was applied for batch injection coulometric measurements of hypochlorite without any dissolved-oxygen interference. Reproducible current vs. time curves were obtained by repetitive measurements of hypochlorite; the relative standard deviation for ten successive measurements was 1.5%. A linear relationship was observed in the concentration range of up to 57 ppm (R² = 0.9997) with a detection limit of 0.18 ppm (S/N = 3). From these results, our proposed coulometric sensor is proven to be very promising for hypochlorite measurements without any dissolved-oxygen interference in practical applications.