Highly selective thiocyanate electrode based on bis-bebzoin-semitriethylenetetraamine binuclear copper(II) complex as neutral carrier

A novel selective thiocyanate PVC membrane electrode based on bis-bebzoin-semitrietliylenetetriamine binuclear copper(II) [Cu(II)(2)-BBSTA] as neutral carrier is reported, which displays an anti-Hofmeister selectivity sequence in following order: SCN- >ClO4- > I- >Sal(-) >SO32- >NO- >HPO4- >Cl- >NO2- >SO42-. The electrode exhibits Nernstian potential linear range to thiocyanate from 1.0 x 10(-1) to 9.0 X 10(-7) with a detection limit 7.0 x 10(-7) mol/l and a slope of -57.0 mV/decade in pH 5.0 of phosphorate buffer solution at 25 degreesC. The response mechanism is discussed in view of the AC impedance technique and the UV spectroscopy technique. From comparison of potentiometric response characteristics between the binuclear metallic complex copper(II) [Cu(II)(2)-BBSTA] and mononuclear copper(II) metallic complex [Cu(II)-BBSDA], an enhanced response towards thiocyanate from the electrode based on binuclear metallic complex copper (II) [Cu(II)(2)-BBSTA] was observed. The electrode based on binuclear copper(II) compound was used to determine the thiocyanate content in waste water with satisfactory results. (C) 2003 Published by Elsevier B.V.