Severinghaus electrode

The Severinghaus electrode is an electrochemical sensor for the quantitative determination of the concentration of carbon dioxide in a solution (or in gases).

Measuring principle

The Severinghaus electrode is a pH electrode , which is preceded by a measuring chamber with a buffer usually made of sodium hydrogen carbonate NaHCO ₃ . Via a gas-permeable membrane, carbon dioxide penetrates from the material to be measured in accordance with the prevailing partial pressure in the buffer solution and shifts its dissociation equilibrium:

${\ displaystyle \ mathrm {CO_ {2} + H_ {2} O \ \ rightleftharpoons \ H_ {2} CO_ {3} \ rightleftharpoons \ HCO_ {3} ^ {-} + H ^ {+}}}$

Therefore, after a short time, a pH value is established in the buffer that depends on the concentration of CO ₂ outside the membrane (see carbon dioxide ).

Individual evidence

↑ John W. Severinghaus, A. Freeman Bradley: Electrodes for blood pO2 and pCO2 determination. In: Journal of Applied Physiology . Vol. 13, No. 3, November 1958, ISSN 8750-7587 , pp. 515-520, online (PDF; 1.1 MB) .

[1] John W. Severinghaus, A. Freeman Bradley: Electrodes for blood pO2 and pCO2 determination. In: Journal of Applied Physiology . Vol. 13, No. 3, November 1958, ISSN 8750-7587 , pp. 515-520, online (PDF; 1.1 MB) .