A PCO₂ Electrode

A PCO₂ electrode:

A) uses coulometric titration to measure the absolute level of CO₂ in blood through the combination of CO₂ with water.
B) is a potentiometric cell in which carbon dioxide gas from the sample diffuses through a membrane and forms carbonic acid.
C) measures the ability of carbonate ions in solution to carry current under the influence of a potential difference.
D) utilizes a gas-permeable membrane to detect CO₂ with very high selectivity over other easily reduced species that might be present in a given sample.