Rigorous Ph Measurement in Non-Aqueous Solution: Measurement Method and Reference Values in Ethanol.

The recently introduced unified pH ( pH_abs^H_2O ) concept enables rigorous pH measurements in non-aqueous and mixed media while at the same time maintaining comparability to the conventional aqueous pH scale. However, its practical application is hindered by a shortage of reference pH_abs^H_2O values. In order to improve this situation, the European Metrology Research Project (EMPIR) UnipHied (“Realisation of a UnipHied pH scale”) launched an interlaboratory comparison among highly experienced electrochemistry expert laboratories to assign the first such reference pH_abs^H_2O values by adopting an extensive statistical treatment of the reported measurement data: to phosphate buffer in water–ethanol mixture (50 wt pH_abs^H_2O measurement. This is an important step towards wider adoption of the pH_abs^H_2O concept in practice, like liquid chromatography, biofuels analysis and electrocatalysis.