THIOCYANATE-SELECTIVE ELECTRODE BASED ON COBALT(II) COMPLEXES OF PYRAZOLONE HETEROCYCLIC SCHIFF-BASES

A new solvent polymeric membrane electrode based on pyrazolone heteroc yclic Schiff base complexes of Co(II) is described. It shows a prefere ntial response towards thiocyanate over a range of 2.0 x 10(-6) to 1.0 x 10(-1) mol L-1 with a slope of -60.2 +/- 0.6 mV/dec. The selectivit y sequence observed is thiocyanate > hydroxide > nitrite > iodide > pe rchlorate > citrate > bromide > fluoride > chloride > nitrate > acetat e > borate > sulfate > phosphate. The selectivity behavior is discusse d in view of axial coordination by uv/vis spectroscopy and the transfe r process of thiocyanate across the membrane interface is investigated by the ac impedance technique. The electrode was successfully applied to the determination of thiocyanate in human urine as an indicator fo r distinguishing between smokers and non-smokers.