Amperometric response to carbon monoxide by a Clark-type oxygen electrode

Hydrogen-conditioned Clark-type electrodes responded amperometrically to carbon monoxide but to a lesser extent than to hydrogen. They lost sensitivity over time at a concentration-dependent rate when exposed to H2 or CO. Maximum electrode current produced by pure CO was 0.45 microA at the optimum polarizing voltage of 0.60 V; electrode sensitivities to H2 and CO were 15 and 1.8 nA, respectively, in 1 microM solutions. These electrodes also responded weakly to acetylene and ethylene. Caution is suggested in interpretation of H2 measurements made with these electrodes if all components of the reaction milieu are not known.