Solid-State Composite reference electrodes

Recently, a collaborative study on the Solid-State Composite reference electrodes was published in the journal of Membranes 2022, 12, 569. Slim Blidi, EACH alumnus and the first author of this publication, provides here a short overview of this novel research.

Potentiometric measurements using conventional electrodes do have some drawbacks when used. This is especially true for the conventional liquid-filled reference electrodes. They are non-robust in use and are maintenance-intensive due to the necessity of refilling the inner solution and keeping the liquid junction clog-free.

By eliminating the liquid component from the electrode structure, Solid-State Composite (SSC) reference electrodes are a viable alternative to conventional reference electrodes. Prepared by either injection molding or chemical polymerization, they are based on a silver/silver chloride reference element enclosed in a polymeric matrix (e.g. polyvinyl acetate) mixed with an inorganic salt (potassium chloride). The composite is the inorganic salt storage material while being in contact with the sample solution.

In this study, a set of the SSC reference electrodes was prepared and their performance was tested in different synthetic solutions to assess the possible influence of pH, solution composition, as well as the concentration and mobility of ions. Using potentiometry and electrochemical impedance spectroscopy methods over a period of several months, stability tests were also performed to evaluate the suitability of the studied SSC reference electrodes for continuous, prolonged, and intensive usage. Concentrations of K+, Na+, Ca2+, and Cl ions and pH values were measured in river water samples at different temperatures using the SSC reference electrodes.

better than commercial liquid-filled reference electrodes in terms of calibration range and actual measurements. It is safe to say that SSC reference electrodes represent the future of potentiometric measurements applied to environmental samples as they are cheap to manufacture and easy to maintain.

I am extremely grateful to my supervisors at Åbo Akademi: Dr. Kim Granholm, Dr. Zekra Moussavi, and Dr. Tomasz Sokalski for their valuable guidance and moral support during the experimental work as well as to the EACH programme for this life-changing experience.


Slim Blidi



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