Ion-sensitive behaviour of silver sulphide-based solid-state copper(II) and iodide electrodes in partially aqueous systems

Abstract

The response of copper(II)- and iodide-selective electrodes was evaluated in various water-organic solvent mixtures. The copper(II) electrode showed an almost Nernstian behaviour in mixtures with ethylene glycol, tert-butanol, propanol, ethanol and methanol. The experimental slopes in buffered water-acetonitrile mixtures were linear but super-Nernstian. The response of this electrode in mixtures with p-dioxane was neither Nernstian nor linear. The interference of mercury(II) in the direct potentiometric titration of copper(II) with EDTA in solution containing acetonitrile was studied. The behaviour of silver sulphide-based iodide electrode hydrophobized by PTFE in mixtures with ethanol, methanol and p-dioxane was poorer than in water. The potential response of the iodide electrode with a homogeneous membrane (Ag2S + AgI) was satisfactory even after prolonged soaking in p-dioxane.