A Differential Potentiometry by the Use of an lon-selective Electrode

Abstract

A differential potentiometry by the use of an ion-selective electrode is described. The procedure is as follows: An indifferent electrolyte is added to a sample solution, reference solution and diluent to have the same ionic strength, individually. The diluent, whose velume is v, is added to the sample solution, whose volume is V, in which the ion-selective electrode and the reference electrode are immersed. The cell emf after each addition of the diluent is plotted against log V. On the same graph the data due tQ similar dilution against the reference solution, whose concentration is C, , are plotted. The emf difference, e which parallels the emf-axis and, is interposed between the two parallel dilution curves, is read off. Thus, the concentration, C. C of the sample solution is given by C.=C, , 10e S where S is the respense slope of the electrode. As an another method, a modified differential potentiometry using the sample solution alone and not the reference solution is also proposed.