Study on new highly selective thiocyanate electrode based on dinuclear copper complex as neutral carriers

A highly thiocyanate-selective poly(vinyl chloride) (PVC) membrane electrode based on N,N'-ethylidene(mu-5,5-methylene-disalicylaldehyde)-acetylacetonedicopper(II) [Cu-2(II)-MDSBAE] complex as neutral carrier is reported. The electrode displays a preferential potentiometric response to thiocyanate and an anti-Hofmeister selectivity sequence in following order: SCN->Sal(-)>I->ClO4->NO3->Br->NO2->Cl-approximate to SO32->SO42-. The electrode exhibits near Nernstian potential linear range of 1.0 x 10-6 similar to 1.0 x 10(-1) mol/L with a detection limit of 8.1 x 10(-7) mol/L and a slope of -53.6 mV/decade in pH 5.0 of phosphorate buffer solution at 25 degrees C. The response mechanism is discussed in view of the alternating current (A.C.) impedance technique. The coordination number and association constants of axial coordination reaction of complex Cu-2(II)-MDSBAE towards SCN-, Sal(-), I-, ClO4- and NO3- were measured by means of the UV spectroscopy technique. The electrode was applied to thiocyanate ion in waste water analysis with satisfactory results.