Theoretical Treatment of the Dynamic Response of Ion-Selective Membrane Electrodes

In order to investigate the parameters affecting the dynamic characteristics of ion-selective membrane electrodes, a theoretical model is evolved. For ion-exchange membranes, this leads to an exponential time-relationship for the response function, whereas a square-root time-dependency is derived in the case of neutral carrier membranes. The speed of response is found to depend mainly on the stirring rate and on the direction of sample-activity change. For carrier membranes, the extraction capacity is shown to be an additional parameter determining the response time. The Influence of non-interfering or interfering species in the sample is discussed. Measurements on the dynamic response of K+-selectlve carrier membrane electrodes are reported which are in excellent agreement with theoretical results and confirm clearly the particular behavior of carrier membranes. © 1975, American Chemical Society. All rights reserved