title: Influence of lipophilic inert electrolytes on the selectivity of polymer membrane electrodes.
abstract: Lipophilic inert electrolytes, i.e., salts without ion-exchange properties, may influence the selectivity of ionophore-based liquid membrane electrodes by affecting the activity coefficients in the organic phase. It is expected by a theoretical model that the addition of a lipophilic salt renders the ion-selective electrode more selective for divalent over monovalent ions. These predictions are confirmed with Ca(2+)-responsive membranes containing the ionophores ETH 2120, ETH 1001, and ETH 129. The effect is especially pronounced with nonpolar membrane phases containing a low concentration of charged species, where up to 2 orders of magnitude selectivity improvement is observed.
authors.affiliation: Department of Organic Chemistry, Swiss Federal Institute of Technology (ETH), Universitätstrasse 16, CH-8092 Zürich, Switzerland, and Department of Chemistry, Auburn University, Auburn, Alabama 36849.
authors.forename: M
authors.initials: M
authors.lastname: Nägele
authors.forename: Y
authors.initials: Y
authors.lastname: Mi
authors.forename: E
authors.initials: E
authors.lastname: Bakker
authors.forename: E
authors.initials: E
authors.lastname: Pretsch