Abstract
The determination of pH values suffers from two sources of error. One is the method of calibration of glass electrode cells. Multiple point calibration with linear regression is highly recommended instead of the usual bracketing procedure in cases where a precision of Δ pH<±0.02 is required. Advantages of this method are discussed, particularly regarding the contribution of the liquid junction potentials to the cell emf. The second uncertainty is caused by batch to batch variations of Standard Reference Materials and their respective standard pH(S), actual values of which are part of the data set of microprocessor-controlled pH meters. Differential potentiometry is proposed as the method of choice to avoid these differences. It results in pH(S) independent of a particular material. Experimental data of the restandardization of pH reference materials are also presented.
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Naumann, R., Alexander-Weber, C. & Baucke, F.G.K. The standardization of pH measurements. Fresenius J Anal Chem 349, 603–606 (1994). https://doi.org/10.1007/BF00323464
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DOI: https://doi.org/10.1007/BF00323464