RESPONSE-TIME CHARACTERISTICS OF THE PCO2 ELECTRODE

The Influence of solution temperature, carbonic acid-aqueous CO2 equilibrium, the internal filling solution sodium bicarbonate concentration, on the rate of response of a Severinghaus-type pCO2 electrode was investigated. Existing theoretical models for the pCO2 electrode provide a reasonably accurate description of electrode behavior at concentrations of CO2 of greater than 2 mM. Deviations from predicted response time characteristics at lower concentrations of CO2 suggest that diffusion of CO2 in dimethyl silicon polymer membrane and diffusion of H2CO3 from the bulk electrode filling solution into the electrolyte film at the pH sensor also influences the electrode response time. The establishment of the carbonic acid-aqueous CO2 equilibrium in solution had no effect on the pCO2 electrode response time. © 1979, American Chemical Society. All rights reserved.