pH measurement is one of the most common analytical parameters in industrial process control. Temperature affects pH measurement in two key ways: changes in electrode slope and changes in the solution's actual pH value.
Nernst Equation & Temperature
According to the Nernst equation, the theoretical slope of a pH electrode at 25°C is 59.16 mV/pH, and this slope varies linearly with temperature. ATC compensates for this by measuring solution temperature and adjusting the electrode slope in real time.
ATC Limitations
ATC only compensates for the temperature effect on electrode slope — it cannot compensate for actual pH changes in the solution due to temperature. Therefore, the measurement temperature should always be reported alongside pH values.