New membrane perchlorate-selective electrodes containing polyazacycloalkanes as carriers

The polyazacycloalkanes, 1,4,8,11-tetra(n-octyl)-1,4,8,11-tetraazacyclotetradecane (L1), 1,4,7,10,13-penta(n-octyl)-1,4,7,10,13-pentaazacyclopentadecane (L2) and 1,4,7,10,13,16-hexa(n-octyl)-1,4,7,10,13,16-hexaazacyclooctadecane (L3) have been synthesised, characterised and the ability of these polyamines as anion receptors has been studied using them as ionophores in PVC membrane anion-selective electrodes. The PVC membranes containing L1, L2 and L3 gave a linear response in the presence of perchlorate. The EMF response characteristics of these membrane-based perchlorate-selective electrodes and the selectivity coefficients using DOS, DBP or NPOE as plasticisers have been determined. The perchlorate-selective electrodes gave anion-selectivity patterns that basically follow the Hofmeister Series, expect the ISE containing L1 and DOS as plasticiser.