The 5th International Symposium on Environmental Economy and Technology (ISEET-2012)

Sensitive voltammetric and amperometric responses of respiratory toxins at hemin-adsorbed carbon-felt


Yasushi Hasebe , Yue Wang

DOI:10.1016/S1001-0742(12)60128-4

Received January 24, 2012,Revised March 07, 2013, Accepted , Available online June 06, 2013

Volume ,2013,Pages 1055-1062

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 μm 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/AgCl 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 O2 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 μmol/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.

Copyright © Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.京ICP备05002858号-3