Potentiometry

Abstract

In potentiometry, the potential of a suitable indicator electrode is measured versus a reference electrode, i.e. an electrode with a constant potential. Whereas the indicator electrode is in direct contact with the analyte solution, the reference electrode is usually separated from the analyte solution by a salt bridge of various forms. The electrode potential of the indicator electrode is normally directly proportional to the logarithm of the activity of the analyte in the solution. Potentiometric methods have been and are still frequently used to indicate the end point of titrations. This use has been known since the end of the nineteenth century. Direct potentiometric determinations using ion-selective electrodes were mainly developed in the second half of the twentieth century.