Preparation of anion selective membrane electrodes from Donnan failure phenomenon induced by copper(II) ion

Abstract

The fabrication of anion selective electrode using mono- and dinuclear metal complexes based on calix[4]arene and anthracene with different number of side-arms and donor atoms were used as ionophores or ion-carriers. The polymeric membrane containing the ionophore L1 and potassium tetrakis(p-chlorophenyl)borate (KTpClPB) as a cation exchanger in the presence of metal ions as triggers showed the Donnan exclusion failure phenomenon. The ionophore L1 bound metal ions very tightly inducing the co-extraction of anions into the membrane and changed the permselectivity of the membrane to anions by the observation of negative EMF responses. However, the membranes containing L2 – L4 gave the positive EMF responses to most metal salts. The best perchlorate anion selective electrode was accomplished using ionophore L1 and 25 mol% of KTpClPB related to the ionophore incorporated in the o-NPOE plasticized PVC membrane preconditioned in CuCl2 with Nernstian slope of -55.80 ± 0.36 mV/decade, over the concentration range of 10-5 – 10-2 M and the limit of detection of 2.84 μM. In addition, the fabricated membrane electrode could be used in the pH range of 3 – 9 with great reversibility and successfully applied to determine the concentration of perchlorate in tap water with satisfactory results.