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, <i>ortho</i>-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:<i>o</i>-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 <i>M</i> with the Nernstian slope of 29.5±0.5 mV per decade of Cu²⁺ and a detection limit of 7.4×10^-8 <i>M</i>. 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 <i>p</i>H 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.