Poly o -toluidine zirconium(IV) iodosulfosalicylate-based ion-selective membrane electrode for potentiometric determination of Cr(III) ions and its analytical applications

Abstract

Poly o-toluidine zirconium(IV) iodosulfosalicylate (PTZIS) is a hybrid inorganic-organic composite cation exchanger, which was synthesized by mixing an organic compound, poly o-toluidine, into the matrices of zirconium(IV) iodosulfosalicylate. On the basis of distribution coefficient, Kd, the material was found to have high affinity for adsorption of Cr(III) ion. Due to its Cr(III) selective nature, ion exchanger was used as an electroactive material for preparation of an ion-selective membrane electrode. The physical properties of membrane were determined by XRD, SEM, and AFM analysis, which indicates that PVC-based Cr(III) ion-selective membrane is amorphous and porous in nature. The electrode responds to Cr(III) in a linear range from 3.16 × 10-6 to 1 × 10-1 M with a Nernstian slope of 22 ± 0.5 mV per decade change in concentration and a detection limit of 1.584 × 10-6 M. The life span of the electrode is found to be 12 weeks. The proposed electrode shows satisfactory performance over a pH range of 3.0-7.0, with a fast response time of 10s. The sensor has been applied to determination of Cr(III) ions in water samples of different origins. The sensor has been used as an indicator electrode in potentiometric titrations of Cr(III) ion with EDTA.