The principles of creating ion-selective electrodes for a-amino acids in a historical retrospective are considered. It is shown that until recently, when the creation of potentiometric membrane sensors, the main emphasis was made on the formation of more selective sensors able to selectively determine the concentration of some analyte in multi-component systems. The material for such sensors were ionselective membranes, which were created specific to a particular analite, but were not specific to the entire class of such analyzers.
