| Abstract
| - Lipophilic inert electrolytes, i.e., salts without ion-exchange properties, may influence the selectivity ofionophore-based liquid membrane electrodes by affectingthe activity coefficients in the organic phase. It isexpectedby a theoretical model that the addition of a lipophilicsaltrenders the ion-selective electrode more selective fordivalent over monovalent ions. These predictions areconfirmed with Ca2+-responsive membranescontainingthe ionophores ETH 2120, ETH 1001, and ETH 129. Theeffect is especially pronounced with nonpolar membranephases containing a low concentration of charged species,where up to 2 orders of magnitude selectivity improvement is observed.
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