A hemin [iron-Fe（III） protoporphyrin IX chloride] was adsorbed onto a carbon-felt （CF）, which is a microelectrode ensemble of micro carbon fiber （ca. 7 ~tm diameter）. The resulting hemin-adsorbed-CF （hemin-CF）...A hemin [iron-Fe（III） protoporphyrin IX chloride] was adsorbed onto a carbon-felt （CF）, which is a microelectrode ensemble of micro carbon fiber （ca. 7 ~tm diameter）. The resulting hemin-adsorbed-CF （hemin-CF） showed a well-defined redox wave based on the hemin- Fe（III）/Fe（II） redox process with the formal potential of -0.225 V vs. Ag/AgC1 in deoxygenated phosphate]citrate buffer solution （0.1 mol/L, pH 5.0）. The apparent heterogenous electron transfer rate constant was estimated to be 8.6 sec-1. In air-saturated electrolyte solution, the hemin-CF exhibited an excellent electrocatalytic activity for the reduction of dioxygen （O2）. This activity was reversibly inhibited by respiratory toxins such as cyanide and azide, which bind sixth coordination position of iron active center of hemin. The electrocatalytic Oz reduction current at the hemin-CF was modulated by the toxins in a concentration-depending manner. Based on the relationship between the %inhibition and the toxin concentration, apparent inhibition constants of cyanide and azide were evaluated to be 4.52 and 1.98 Ixmol/L, respectively. When the hemin-CF was used as a working electrode unit of the CF-based electrochemical flow-through detector with air-saturated carrier, the injection of the azide induced peak-shape current responses, which allowed rapid and continuous flow-amperometric determination of azide with high sensitivity.展开更多
基金supported in part by the NEXT-supported Program for the Strategic Research Foundationat Private Universities,2011-2015
文摘A hemin [iron-Fe（III） protoporphyrin IX chloride] was adsorbed onto a carbon-felt （CF）, which is a microelectrode ensemble of micro carbon fiber （ca. 7 ~tm diameter）. The resulting hemin-adsorbed-CF （hemin-CF） showed a well-defined redox wave based on the hemin- Fe（III）/Fe（II） redox process with the formal potential of -0.225 V vs. Ag/AgC1 in deoxygenated phosphate]citrate buffer solution （0.1 mol/L, pH 5.0）. The apparent heterogenous electron transfer rate constant was estimated to be 8.6 sec-1. In air-saturated electrolyte solution, the hemin-CF exhibited an excellent electrocatalytic activity for the reduction of dioxygen （O2）. This activity was reversibly inhibited by respiratory toxins such as cyanide and azide, which bind sixth coordination position of iron active center of hemin. The electrocatalytic Oz reduction current at the hemin-CF was modulated by the toxins in a concentration-depending manner. Based on the relationship between the %inhibition and the toxin concentration, apparent inhibition constants of cyanide and azide were evaluated to be 4.52 and 1.98 Ixmol/L, respectively. When the hemin-CF was used as a working electrode unit of the CF-based electrochemical flow-through detector with air-saturated carrier, the injection of the azide induced peak-shape current responses, which allowed rapid and continuous flow-amperometric determination of azide with high sensitivity.
