Potentiometric sensors are an important class of electrochemical sensors, which detect the relationship between the activity of analyte species and the observed potential response with the two-electrode system comprising an indicator electrode and a reference electrode. Ion-selective electrodes (ISEs) with polymeric membranes containing selective carriers (ionophores) are the most commonly-used potentiometric sensors. They have been widely used for directly determining various inorganic and organic ions in medical, environmental and industrial analyses .