Nonmonotonic Transient Potential Signals with an 18‐Crown‐6 based Ion‐Selective Electrode in a Flow‐Injection System

The dynamic potential response of an 18‐crown‐6 based ion‐selective electrode towards Li⁺, Na⁺, K⁺ and Ca²⁺, in a flow‐injection system is studied. Different double nonmonotonic transient signals are obtained for the different ions. The influence of the flow‐injection variables and of ion concentration on the signals is studied. Two signal parameters, the relative return rates, are found to be characteristic for each ion and are constant for a concentration range of 1–3 decades. The nonmomotonic transient signals obtained are explained by reference to the theoretical models reported.