7. Potentiometric measurements at zero or impressed current

The indications of the different types of indicator electrodes are exploited:

• or to directly relate the potential read to the concentration of the solute(s) through prior calibration (potentiometric assays);

• or to determine the quantity of a substance by means of a chemical reaction (potentiometric titrations).

Depending on the operating conditions, there are two main types of potentiometric measurement:

• zero-current potentiometry, with one indicator electrode (and one reference electrode) or two indicator electrodes (generally of different types);

• impressed current potentiometry, with one indicator electrode (and one reference electrode) or two indicator electrodes (usually of the same type)....