ABSTRACT
The term "ion-selective electrodes" is applied to a range of membrane electrodes which respond selectively towards one ion species in the presence of others. The formerly used but less preferred term "ion-specific" is not favored' because these electrodes are rarely specific in their response to one ionic species over others, although this is a desirable property sought by the designer of new electrodes. Although the current interest in ion-selective electrodes may be said to have arisen in the period from 1966 to 1967 with the announcement by Frant and Ross of the fluoride- and calcium-responsive electrodes, these developments are in fact the culmination of studies by many workers going back to the turn of the century. Students of the history of ideas might ponder why the new developments took so long. The answer probably lies in the delayed advances in related fields.
