Identify which, if any, of the measuring electrodes in a blood gas analyzer has/have the following attributes. Circle, highlight, or boldface the appropriate electrodes:
1. **pH** PCO2 PO2 involve pH measurement
2. pH **PCO2** PO2 involve a current measurement (amperometric)
3. pH PCO2 **PO2** involve a voltage measurement
4. pH PCO2 **PO2** require a semi-permeable silicone membrane
5. pH PCO2 **PO2** incorporates an integral/self-contained reference or counter-electrode
6. pH PCO2 **PO2** utilizes a separate independent reference electrode
7. pH PCO2 **PO2** involves a chemical reaction at the electrode surface
8. pH PCO2 **PO2** requires an external applied voltage to enable signal measurement
9. pH PCO2 **PO2** signal governed by the Nernst Equation
10. pH **PCO2** **PO2** referred to as the Severinghaus and Clark electrodes, respectively
11. pH PCO2 **PO2** requires only a one-point calibration
12. pH PCO2 **PO2** made of platinum
13. pH PCO2 **PO2** measured at 37 deg C.
14. pH PCO2 **PO2** uses liquid buffers for calibration
15. pH PCO2 **PO2** calibration setpoint generally dependent on barometric pressure