ABSTRACT
Techniques based on the measurement of potential of a sensor are termed potentiometry. In a potentiometric type of sensor a membrane or sensor surface (indicator electrode) acts as a half-cell, generating a potential proportional to the logarithm of the analyte activity. The indicator electrode is connected directly with a reference electrode to form a galvanic cell. Potentiometric methods belong to two major types: Direct potentiometry and Indirect potentiometry or potentiometric titration. The solid-state fluoride electrode has found extensive use in the determination of fluoride in a variety of materials. The potassium Ion-Selective Electrode (ISE) is a liquid-type membrane electrode. The ISE which incorporates a neutral carrier-based ionophore, valinomycin, or a bis-crown-ether derivative, separates the solution being measured from the electrode internal filling solution. The potassium electrode responds to cations that are complexed by the ionophore and thus can compete in the generation of the boundary potential.
