Triiodide-selective polymeric membrane electrodes based on Schiff base complexes of Cu (II) and Fe (III)

Abstract

Poly(vinyl chloride) (PVC) membrane electrodes based on two complexes of Schiff base 2,2′[4,4′-diphenylmethane bis (nitromethylidyne)] bisphenol, L, with copper (II) and iron (III) ions were prepared, characterized and used for determination of triiodide ions. The electrodes based on CuL and FeL complexes show an anionic response slope of −60 mV per decade in a linear activity range 6.0×10−1 to 8.0×10−6 mol l−1 and 5.0×10−1 to 1.0×10−5 mol l−1 to triiodide ion with lower detection limits of 4.0×10−6 and 6.0×10−6 mol dm−3, respectively. The proposed electrodes have fast response time (15 s) and their responses are independent of pH of the test solution in the range 3.5–9.0. The electrodes revealed very good selectivities for triiodide ion over a variety of anions. They were used as an indicator electrode in the potentiometric titration of triiodide ions and determination of ascorbic acid in Vitamin C tablet.