A Selective Membrane Electrode for Thiocyanate Ion Based on a Bis‐taurine‐salicylic Binuclear Copper(II) Complex as Ionophore

Abstract

AbstractThe response characteristics of a new potentiometric membrane electrode with unique selectivity towards thiocyanate ion were reported. The electrode was prepared by incorporating bis‐taurine‐salicylic binuclear copper(II) complex into a plasticized PVC‐membrane. The resulting electrode exhibits anti‐Hofmeister selectivity sequence: SCN−>I−>ClO4−>Sal−>NO3−>NO2−>Br−>Cl−>SO3−>SO42− and a near‐Nernstian potential linear range for thiocyanate from 1.0Å×10−1 to 1.0Å×10−6 mol·L‐1 with a detection limit of 8.0Å×10−7 mol·L−1 and a slope of −56.5 mV/pc in phosphate buffer solution of pH 5.0 at 20°C. The UV/Vis spectra, IR spectroscopy and AC impedance studies showed that the excellent selectivity to thiocyanate was related to the unique interaction between the central metal and the analyte and a steric effect associated with the structure of the carrier. The electrode was successfully applied to the determination of thiocyanate in waste water and human urine samples.