A new highly selective thiocyanate electrode based on benzaldehyde semicarbazone copper ( E ) complex [Cu( II )-BASA] as neutral carrier is developed, which displays an anti-Hofmeister selectivity sequence: SCN~- > ClO_4~- > I~- > Sal~- > Br~- > NO_3~- > Cl~- > NO_2~- > SO_3~ (2-) > SO_4~(2-) > H_2PO_4~-. The electrode exhibits Nemstian potential linear range to thiocyanate from 1.0 * 10~(-1) to 8.0 * 10~(-6) mol/L with a detection limit 3.0 * 10~(-6) mol/L and a slope of 56.0 mV/pSCN~- in phosphate buffer solution (pH 6.0) at 28℃ . The response mechanism is discussed in view of a. c. impedance technique and UV spectroscopy technique. These deviations result from the direct interaction between the central metal and the analyte ions and the steric effect associated with the structure of the carrier. The electrode has the advantages of simplicity, fast response, fair stability and reproducibility and low detection limit. The electrode can be applied to waste water analysis and the result obtained exhibits fair agreement with the result given by HPLC methods.

Key words: BENZALDEHYDE P, SEMICARBAZONE P, COPPER COMPOUNDS, ION SELECTIVE ELECTRODE, THIOCYANIC ACID, UV