Temperature has a number of significant effects on pH measurement. Analysts must have an appreciation
of these effects so that they can improve and maximise the accuracy of their pH measurements. Automatic
Temperature Compensation (ATC) should always be utilised during calibration to correct for the nonNernstian
slope of electrodes. For pH meters that feature automatic buffer recognition, the correct
calibration buffers, as specified by the instrument manufacturer, must always be used as the meter has the
temperature profile for these buffers stored in memory. Additional sources of error include the calibration
isopotential point, thermal or chemical equilibrium effects on the electrode and the temperature coefficient
of variation on buffers and samples. To reduce these potential errors, instrument calibration and sample
measurement should be performed at the same temperature ideally using a water bath. Also, as the pH of
solutions is temperature dependent, the measurement temperature should always be recorded.
Implementation of these simple guidelines will lead to either a reduction or elimination of the problems
associated with temperature. This will result in improved accuracy in pH results thus giving the user greater
confidence in their pH measurements. Depending on the decisions made based on the pH readings the
consequences of inaccurate pH measurement can be more than just a waste of the analysts’ time.