title: Evaluation of some new 14- and 15-crown-formazans as carriers in cesium ion selective electrodes.
abstract: A number of new crown-formazans with 14 and 15 membered rings have been investigated as selective neutral carriers in cesium ion selective electrodes. Two plasticizers (NPOE and NPBnE) were studied. The new 14-crown-formazan 4a containing the 4-pyridyl N-oxide at the formazyl carbon exhibited the highest selectivity in cesium ion selective electrodes, especially towards the two low selectivity monovalent ions K(+) and NH4(+). Also, membranes containing the plasticizer NPBnE showed better cesium selectivity relative to most ions than those containing NPOE. Membranes containing 4a and variable compositions of plasticizers, potassium tetrakis-(p-chlorophenyl)borate (KTpClPB), and trioctylphosphine oxide (TOPO) were studied in order to prepare an electrode with the optimum cesium selectivity. The highest selectivity for cesium was achieved with the two electrodes designated d and e with membranes containing the ionophore 4a, NPBnE and KTpClPB with and without TOPO. Selectivities are reported relative to sodium, potassium, barium, calcium, ammonium, lithium, cobalt, and magnesium.
authors.affiliation: Department of Chemistry, Faculty of Science, Cairo University, Giza, Egypt.
authors.forename: B N
authors.initials: BN
authors.lastname: Barsoum
authors.forename: S K
authors.initials: SK
authors.lastname: Khella
authors.forename: A H
authors.initials: AH
authors.lastname: Elwaby
authors.forename: A A
authors.initials: AA
authors.lastname: Abbas
authors.forename: Y A
authors.initials: YA
authors.lastname: Ibrahim