K. Toth et al., ANALYTICAL PERFORMANCES OF LIPOPHILIC DIAMIDES BASED ALKALINE-EARTH ION-SELECTIVE ELECTRODES, Electroanalysis, 5(9-10), 1993, pp. 781-790
Based on complex chemical considerations, lipophilic diamide derivativ
es have been designed and synthesized as ionophores for liquid membran
e electrodes. The structure-selectivity studies revealed that the majo
rity of the ligands exhibit calcium ion selectivity except the compoun
d bis-N,N-dicyclohexyl-malonamide. The latter has an almost equal sele
ctivity for Ca2+ and Mg2+ and sufficiently rejects sodium ions, thus i
t lends itself to water hardness measurements.