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In a perfect pH electrode - one that is zeroed at exactly pH 7 - there is no temperature effect on the electrode sensitivity at pH 7 no matter how much the temperature changes. Most pH electrodes are not perfect, but the errors from changes in temperature are still very minute when near pH 7, plus or minus one-tenths of a pH, and can be disregarded. However, the further from pH 7 the solution is and the greater the temperature changes, the greater the measurement error due to changes in the electrode's sensitivity. To compensate for this error, the changes in electrode sensitivity due to changes in temperature can be calculated using the formula given below:

For a conventional glass electrode, the impact on temperature compensation is 0.003 pH /°C / pH away from pH 7. For example, if the electrode is calibrated at room temperature (25 °C) and is measuring a sample around pH 4 at around 5 °C.

Temperature difference: 25°C - 5°C = 20 °C
pH away from neutral: 7pH - 4pH = 3 pH

Total error: 0.003 x 20 x 3 = 0.18 pH

This error value of 0.18 pH should be taken into consideration to derive the actual pH reading of the sample.

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