Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Cubane diester crown ethers were tested as ion-selective electrodes in poly(vinyl chloride) (PVC) membranes. The four ionophores studied proved to be good K+ neutral carriers, showing Nernstian and near-Nernstian responses to this ion, in the range 10-4-10-1 M. The fixed interferences method was used to determine relative selectivity coefficients for all the electrodes. The highest selectivity for potassium relative to sodium, lithium, calcium and magnesium ions using potassium tetrakis(p-chlorophenyl)borate (KTpClPB) as a resistance modifier and NPOE as a plasticizer was obtained with the 1,4-cubyl diester-25-crown-7 ether ionophore. The effects of KTpCIPB on membrane selectivity were assessed; its removal was found to increase the selectivity of the four ionophores for potassium relative to cesium, sodium, calcium and magnesium ions with minimal effects on lithium and ammonium ions. The compounds tested exhibited a fast Nernstian response to changes in K+ concentration which was stable to within 〈100 μV h-1.
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