Absolute pH-measurement principle
pH determination is a potentiometric (electrochemical) analysis method. A typical measuring setup with absolute pH probes comprises two electrodes – a measuring electrode immersed in a process medium and a reference electrode immersed in an electrolyte liquid. The measuring electrode generates a potential that clearly identifies the chemical condition (hydrogen ion concentration) of the medium to be measured. The reference electrode provides a constant identified potential that is independent of the composition of the process medium.
A transmitter connected to the pH measuring probe calculates the medium’s pH value from the difference in potential between the two electrodes, and in dependence of the measured temperature – the pH value is now an absolute pH value.