Design and construction of ion-selective electrode based on a new Schiff base and its application in determination of copper(II) ions

Abstract

A copper(II) selective sensor has been made from polyvinyl chloride matrix membrane based on the carrier, 2-(5-bromo-2-hyroxybenzylidineamino) pyridine 3-ol as an ionophore, ortho-nitrophenyl octyl ether (o-NPOE) as mediator solvent and sodium tetraphenylborate (NaTPB) as additive. The best performance is presented by membrane of composition of ionophore (Schiff base):PVC:o-NPOE:NaTPB of 3:33:63:1 (by weight). The membrane potential response is linear in the concentration range of 1.0×10^-7 to 1.0×10^-2 M with the Nernstian slope of 29.5±0.5 mV per decade of Cu²⁺ and a detection limit of 7.4×10^-8 M. The response time of the sensor is very short; less than 10 s, and it can be used for at least 8 weeks without any difference in potential. The proposed copper(II) selective electrode displays excellent selectivity towards alkali, alkaline earth and transition metal ions and can be used in the pH range of 4-7. It has been successfully used as an indicator electrode for the determination of Cu(II) in water samples. The electrode has also been employed as an indicator electrode in titration of Cu²⁺ with EDTA.