Potentiometric Sensors for Pr(III) Based onN-N᾽o-Phenylene-bis(salicylideneimine) Using Epoxy Resin and PVC as Binding Materials

Praseodymium(III) ion selective electrodes have been prepared using N-N᾽o-phenylene-bis(salicylideneimine) as a suitable electro-active material. Several membranes comprising of varying compositions of electro-active material with epoxy resin and polyvinylchloride (PVC) as binding materials were prepared. However the one with composition 50% Schiff᾽s base and 50% binder was found to exhibit best performance. The sensor with epoxy resin as binder presents a linear dynamic range of 1.0×10-6 to 1.0×10-1 M with a Nernstian slope of 19.9 mV/decade. The sensor has a quick response time. (less than 10 s). The reproducibility of the electrode is about 6 months without any considerable, noticeable potential divergence. The sensor is effective in pH range of 3.00-8.62. In case of PVC as binding material; the results are compared for same composition of electro-active material. The sensor presents a linear dynamic range of 1.0×10-6 to 1.0×10-1 M with a slope of 14.0 mV/decade. The response time of the sensor is found to be 20s with a reproducibility of 4 months. The sensor is effective in pH range of 2.97-8.90. Effect of internal solution was studied and both the electrodes could satisfactorily be used in partially non-aqueous medium. Selectivity coefficients for both the electrodes have been determined by FIM (fixed interference method) with respect to many rare earth metal ions, alkali & alkaline earth metal ions and some transition metal ions. Both the electrodes were successfully employed as indicator electrode in the potentiometric titration of Pr(III) ions with oxalic acid and EDTA.