LEAD-SELECTIVE POLY(VINYL CHLORIDE) MEMBRANE ELECTRODES BASED ON ACYCLIC DIBENZOPOLYETHER DIAMIDES

Lipophilic acyclic dibenzopolyether diamides, 12 kinds, have been desi gned to prepare solvent polymeric membrane ion-selective electrodes (I SEs) for Pb2+. The ionophores include (N,N-dialkylcarbamoylmethoxy)phe noxy]3-oxapentanes 1-4, alkylcarbamoylpentadecyloxy)phenoxy]-3-oxapent anes 5-8, and -N,N-dialkylcarbamoylpentadecyloxy)phenoxy]ethanes 9-12. Linear response concentration range of the ISE based on 9 is 3 x 10(- 2)-1 x 10(-6) M of Pb2+ (average slope = 28.5 mV decade(-1)). Potentio metric selectivities of the ISEs based on 1-12 for Pb2+ over other hea vy metal cations, alkali metal cations, and alkaline earth metal catio ns have been assessed. These ISEs exhibit remarkably high selectivitie s for Pb2+ relative to heavy metal cations, such as Cu2+, Fe2+, and Ni 2+, the selectivity coefficients (K-Pb,Cu(Pot)) being 5 x 10(-5)-6 x 1 0(-5) for 1-4 and ca. 6 x 10(-4) for 9. For the Pb2+ selectivities ove r alkali metal cations, such as Na+ and K+, 9 which has an ethylene gl ycol spacer and a N,N-diethyl group is superior to other dibenzopolyet her diamide ionophores 1-8 and 10-12. (C) 1997 Elsevier Science B.V.