TOWARDS A SOLID-STATE REFERENCE ELECTRODE

The construction of a solid state reference electrode is presented. Th e solid state reference electrode has two membranes arranged in parall el. The membranes are anion and cation conducting, and both of them ar e in contact with the sample solution. Resistors with considerably lar ger resistance than that of the ion-exchange membranes are soldered on to each of the two electrode parts, to give the same amount of charge transferred in the parallel paths. The anion and cation conducting pat hs of the electrode then give contributions to the e.m.f. that cancel, and we show that the cell e.m.f. varies with the concentration of the ion reversible to the ion selective electrode (ISE) in a Nernstian wa y. As an example of the ISE we have studied a fluoride selective elect rode. We have also tested materials for the anion and cation conductin g parts of the reference electrode, and found that they behave close t o what is predicted. The performance of the total reference electrode can be compared to a commercially available electrode. Procedures for further progress in the realization of the ideal reference electrode a re discussed on the background of our theoretical development. (C) 199 7 Published by Elsevier Science S.A.