SOLID POTENTIOMETRIC PH-ELECTRODE

Potentiometric pH-glass electrodes are among the most reliable so far known. Most remaining disadvantages (e.g. limited operating temperature, minimum size) stem from their aqueous component (reference buffer). The purpose of this investigation is therefore to maintain glass as a menbrane with outstandingly good sensing properties but to replace the reference buffer, including the Ag/AgCl electrode, by a solid contact providing a reversible transition from the ionic to the electronic part of the sensor The problems in making such a contact are discussed in terms of thermodynamic and kinetic parameters. The properties of glass electrodes contacted with the materials belonging to the Li, Ag, I ternary system are presented. They are compared with those of conventional pH-electrodes and pH-FETs. The advantages arising from the chemical stability of the contact with the glass membrane are outlined