The hydrogen ion response of the glass electrode in alkaline solutions

Abstract

Soon after the demonstration of the suitability of the glass electrode for measuring pH it was found that it had. the disadvantage of showing deviations from the 59mV per pH unit response in acid (pH<2) and alkaline (pH >9) solutions. Early in the development of the electrode as an analytical tool a great deal of work was carried out on the nature of these deviations. Howevert examination of the literature of 20 years ago reveals several discrepancies between the data obtained by different investigators, notably concerning the behaviour of electrodes made from lithia glass and the magnitudes of the errors shown by soda glass electrodes in different acid solutions. Although the major discrepancies have now been resolved, they clearly underline the unreliability of the early work as a whole. The whole question of the errors of pH responsive glass electrodes has therefore been re-exanined in this department using modern electronic measuring equipment and a recently developed and proven experimental technique which enables variations in the glass electrode potential to be followed relative to a hydrogen electrode immediately after placing the glass electrode in a solution.