Lead-selective membrane electrodes based on neutral carriers. Part I. Acyclic amides and oxamides

Abstract

A group of amides and oxamides has been used as potential ionophores for lead ions in solvent polymeric membrane electrodes. The most favourable analytical results (slope, log k_Pb,_M and lifetime) were obtained with membranes incorporating ionophore ETH 295 and potassium tetrakis(p-chlorophenyl)borate. With the use of these membranes: (i) a linear response with a slope of 35.3 mV per pPb unit in Pb^II and an activity range of 10^–5.2–10^–1.0M were obtained; (ii) the selectivity factors (log k_Pb,_M) were lower than –1.5 with respect to the ions studied (with the exception of Ag⁺ and H⁺ ions); (iii) the electrodes can be used with no change in their properties for at least 2 months.