Liquid Membrane Electrodes

Liquid Membrane Electrodes

Initially, researchers tried to use glass membrane electrodes (which were successful for monovalent cations such as H⁺ and Na⁺) to detect divalent cations, such as Ca⁺. When this was unfunctional, liquid Membranes were developed.

Liquid membrane electrode works by an ion exchange process. Liquid ion exchange membrane has functional groups to form coordination complexes.

The inner solution containing a known concentration of the ion is placed in a glass tube fitted with Ag/AgCI electrodes selective to it. The outer aqueous solution is separated from the inner solution by a liquid ion exchange membrane.

The membrane seals the bottom of the electrode vessel. The outer compartment contains the organic liquid ion exchanger. Without the exchanger, the ion of interest is unable to penetrate the membrane.

Calcium Ion-selective electrodes are commonly used to measure calcium ion activity in biological fluids, as calcium ion is important in many physiological processes.