POLY(VINYL) CHLORIDE MEMBRANE CESIUM-SELECTIVE ELECTRODES BASED ON DOUBLY CROWNED 1,3-CALIX[4]ARENES

Two calix[4]arenebiscrown-6 derivatives in the 1,3-alternate conformat ion were tested as caesium-selective ionophores in poly(vinyl) chlorid e (PVC) membrane electrodes. The ionophores were 1,3-calix[4]biscrown- 6 (BC6) and 1,3-calix[4]bisnaphthylcrown-6 (BC6N). PVC membranes plast icised with o-nitrophenyl octyl ether and without lipophilic salt addi tives were used throughout this study. These ligands produced electrod es with Nemstian behaviour. The selectivity coefficients for caesium w ith respect to alkali, alkaline earth, hydrogen and ammonium ions were determined. The effects of counteranions on the electrodes' performan ce were also studied. The electrodes' response demonstrated the abilit y of the ligands to act as neutral carriers independent of the presenc e of lipophilic salts in the membrane phase and Cl- or NO3- in the tes t solution. Better results than those previously reported with other l igands in terms of detection limit (3x10(-7) M) and Cs/Na selectivity (K-pot of 1.1x10(-5) and 7.4x10(-6) for BC6 and BC6N, respectively) we re found for the doubly crowned 1,3-calixarenes. (C) 1998 Elsevier Sci ence B.V. All rights reserved.