The temperature of the solution modifies the pH value (see Table 2) and the electrical potential which is measured by the electrode. Therefore, the measurement has to be corrected by means of a mechanism for automatic compensation, by connecting a temperature probe to the pH-meter. Some pH-meters have their own mechanism to measure the temperature and correct the pH value accordingly. Other pH-meters need the temperature value to be inserted manually by the operator before the pH measurement.
Only equipment which has this mechanism can measure the different temperatures in the calibration accurately. Finally it is worth remembering that the rapid swings in the temperatures affect the time taken to respond the electrode. It is advisable to indicate the temperature at the time the measurement of the ph is taken.