Reference electrodes with polymeric membranes containing ionic liquids of various physicochemical properties

In this paper, the development of reference electrodes with polyurethane membranes containing ionic liquids is described. In particular, the influence of physicochemical properties of ionic liquids on the performance of polymeric membrane reference electrodes was elucidated. It was found that the potential stability of tested electrodes strongly depends on the differences in partition coefficient values between cation and anion of the ionic liquid. Among tested ionic liquids, 1-(2-hydroxyethyl)− 3-imidazolium bis{(trifluoromethyl)sulfonyl}imide induced the best potential stability of reference electrodes. It was also shown that the amount of the ionic liquid in the polymeric membrane does not influence significantly the performance of resulting reference electrodes. Moreover, results demonstrate that the addition of the plasticizer to the polyurethane membrane is not necessary to prepare reference electrodes that show sufficiently stable EMF values in solutions of various ion concentrations. Membranes of optimal composition were used to prepare All-Solid-State reference electrodes on glassy carbon disc electrodes with acceptable potential stability.