Final answer:
The PCO2 electrode in a blood gas analyzer employs potentiometry, which measures voltage related to ion concentration without producing significant current. The correct answer is b) Potentiometry.
Step-by-step explanation:
The PCO2 electrode in a blood gas analyzer uses the principle of potentiometry, which is option b) Potentiometry. In potentiometric measurements, a voltage is measured that is directly related to the concentration of a specific ion in solution. The reaction at the electrode surface does not produce a significant current, so it essentially measures the electric potential (voltage) difference without drawing much current.
This is different from other kinds of electrochemical analyses, such as amperometry, which measures current that flows in response to a potential difference, and coulometry, that involves the quantification of charge to determine the amount of matter transformed during an electrochemical reaction. In this case, the PCO2 electrode measures the partial pressure of carbon dioxide in a blood sample by comparing it to a reference electrode. The correct answer is b) Potentiometry.