Application Note

Practical pH Measurements

Source: Thermo Fisher Scientific

In this technical note, the various voltage sources within a pH combination electrode are identified, and the contribution of each to the overall pH loop output voltage is reviewed. Sources of deviation of the pH electrode response from the ideal Nernst equation such as zero offsets and asymmetry potentials are presented. Sources of error caused by temperature dependence and acid or alkaline errors at the pH range extremes are also discussed.