Direct Potentiometry of Polyacrylate with Solid-Membrane Cadmium Ion-Selective Electrode

Three solid-state ISEs (Cd, Pb, Cu) were evaluated for direct potentiometry of polyacrylate. Cd-ISE had a lower pH response but an appreciably high response to PA, while Cu-ISE had a remarkably high pH response but a rather low response to PA. Pb-ISE showed intermediate behaviors. These results suggest direct potentiometry of PA by simultaneous measurements of pH and the Cd-ISE response. Anions of foreign salts may cause positive errors by the interactions with Cd2+, whereas cations of salts may cause negative errors by the interactions with PA. The extent of such errors is, however, negligible in the detection of PA in the circulating water of cooling systems.