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The Project

 Pan-European Network of Fundamental pH Research: UnipHied

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Initiated by the group of Prof. Ivo Leito of the University of Tartu, the pan-European research network of fundamental pH Research UnipHied started in May 2018.

This network is an umbrella covering a range of fundamental and applied research activities carried out at the partner laboratories. It brings together the different research endeavors that are underway and aims at facilitating networking and information exchange between partners.

Why is such network needed? As of now, it is not possible to compare pH values of solutions made in different solvents, as every solvent has its own pH scale resulting from different ΔsolvG°(H+, S) values for each solvent S. This situation is highly unfortunate, since it causes confusion and inaccuracies into many fields, extending far beyond the specific field of acid-base chemistry. Examples are industrial catalytic processes, food chemistry, liquid chromatograpy, etc. The central technical goal of UnipHied is to overcome this situation by developing technical/metrological basis for practical pHabs measurement.

The most important technical objectives of UnipHied are (1) metrology of pHabs measurement (measurement procedure, uncertainty, traceability); (2) reliable method for the experimental or computational evaluation of the liquid junction potential between aqueous and non-aqueous solutions; (3) coherent and validated suite of calibration standards and novel solid state redox pH sensor for a variety of widespread systems (e.g., industrial mixtures, soils/waters, food products, biomaterials); (4) based on the outcome of the project, to contribute to the international specifications for bioethanol quality (e.g. by assigning values to existing certified reference materials) and other relevant standards development organizations, and to disseminate the findings to the European measuremnet infrastructure.

The first version of the pHabs measurement procedure has been created by Agnes Heering (Suu) in the framework of her PhD thesis. A major experimental difficulty has been the evaluation of the liquid junction potential (LJP), which will be thoroughly addressed in the framework of UnipHied. The first important steps towards this goal have very recently been made and published as two back-to-back papers: Angew. Chem. Int. Ed. 2018, 57, 2344–2347 and Angew. Chem. Int. Ed. 2018, 57, 2348–2352 The key achievement described in the papers is finding an ionic liquid, namely [N2225][NTf2], that can be used as salt bridge electrolyte and has such properties that two out of three main sources of LJP are eliminated.

UnipHied is funded from the EMPIR programme (project 17FUN09) co-financed by the participating states and from the European Union's Horizon 2020 research and innovation programme.


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