Switching between voltammetry and potentiometry in order to determine H⁺ or OH^- ion concentration over the entire pH scale by means of tungsten disk electrode

Abstract

This study demonstrates that tungsten rotating disk electrode can be used for pH or H+/OH- concentration measurements in practically entire pH range, using the combination of voltammetric and potentiometric techniques. In strong acidic (c(H+) > 10-3 mol dm -3), and alkaline (c(OH-) > 10-3 mol dm -3) solutions, rotating tungsten disk electrode can be used as a maintenance-free electrode for voltammetric determination of H+ and OH- ion concentration. After an appropriate electrochemical oxidation, the same electrode, in a stationary regime, may be used as a potentiometric sensor in the range 3 < pH < 11, with the response -49.5 ± 2.3 mV per one pH unit. © 2011 Elsevier B.V. All rights reserved.