Calibration of the pO2 electrode requires which standard?

• A. Two gases of known pO2
• B. Two phosphate buffers
• C. Two gases of known pCO2
• D. Two salt solutions

Answer: (A)

Calibration of the pO2 electrode hinges on mapping the sensor’s current to an actual oxygen partial pressure. The electrode’s response comes from oxygen diffusing through its membrane and being reduced at the cathode, producing a current that is proportional to pO2. To turn that current into a correct pO2 value, you need standards where the pO2 is precisely known. Using two gas mixtures with known pO2 provides two reference points, enabling you to establish the slope (sensitivity) and intercept (baseline) of the calibration curve. With these two points, you can accurately convert any measured current into a corresponding pO2 across the measurement range. Phosphate buffers or salt solutions don’t fix the oxygen level, so they can’t anchor the electrode’s response to a true pO2. Gases with known pCO2 are for calibrating CO2-related measurements, not the pO2 electrode.