Copper(II)-selective electrodes based on macrocyclic compounds

Abstract

Poly(vinyl chloride) based membranes of 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene diperchlorate and 3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene diperchlorate with dibutyl phthalate (DBP) and dioctyl phthalate (DOP) as plasticizing solvent mediator show a Nernstian response for Cu²⁺ ions over a wide concentration range (1 × 10^–5–1 × 10^–1 mol l^–1) between pH 1.9 and 5.2. These electrodes have been found to be chemically inert and of adequate stability, with a response time less than 30 s. The electrodes are selective over a large number of cations, including Hg^II, and anions such as Cl^– and Br^– cause no interference. These electrodes work satisfactorily in partially non-aqueous media and have been used as indicator electrodes in potentiometric titrations of Cu²⁺ with EDTA.