Realisation of a Unified pH Scale

Short Name: UnipHied, Project Number: 17FUN09
Image showing pH of a solution bein measured
A scientist measuring the pH of a solution with a handheld meter in a laboratory

Practically implementing a unified method for assessing acidity

pH is one of the most important chemical properties measured in both science and industry, playing a vital role in health, environmental studies, and material reprocessing. With potential to impact an extensive range of sectors, accurate analysis and monitoring of pH is essential.

Due to theoretical and practical constraints, the comparison of pH between different media hasn’t been possible and over the last century this has led to the formation of several incompatible pH scales. In 2010 the concept of a unified acidity scale, pHabs, was devised to overcome this issue, but it has proved challenging to implement.


This project has put pHabs into practice by establishing a reliable and universally applicable procedure for measuring the acidity of any substance.

It also developed a validated set of calibration standards for a wide variety of media.

In striving towards a practical and accurate unified pH scale, this project will support and strengthen EU manufacturing and innovation in industries from pharmaceuticals to petrochemicals and semiconductors.


Coordinator: Daniela Stoica (LNE) 


For more information, please contact the EURAMET Management Support Unit:

Phone: +44 20 8943 6666


Project website
Strengths of Acids in Acetonitrile

European Journal of Organic Chemistry

The Inverted Philosopher’s Stone: how to turn silver to a base metal

Journal of Solid State Electrochemistry

Biphasic pKa Values

Croatica Chemica Acta

Other Participants
Albert-Ludwigs-Universität Freiburg (Germany)
ANB Sensors Limited (United Kingdom)
FCiências.ID - Associação para a Investigação e Desenvolvimento de Ciências (Portugal)
Tartu Ulikool (Estonia)