A highly selective polymeric membrane barium(II) electrode based on a macrocyclic tetrabasic ligand as neutral carrier.

A novel barium(II) ion-selective polymeric membrane electrode based on a macrocyclic tetrabasic ligand that derived from the reaction of 4,6-diacetylresorcinol and ethylenediamine in the molar ratio 1:1 as neutral carrier was described. The electrode, with optimum membrane composition, exhibited an excellent near-Nernstian response for Ba(2+) ion ranging from 3.6 x 10(-6) to 1.0 x 10(-1) mol/L with a detection limit of 1.9 x 10(-6) mol/L and a slope of 29.7 +/- 0.2 mV/dec in pH 4.0 nitrate buffer solution at 25 degrees C. It had a relatively fast response time (10 s), good selectivity towards Ba(2+) ion, and could be used over a wide pH range of 2.5-7.5. Then, the response mechanism was discussed in view of UV-visible spectroscopy and the A.C. impedance technique. Finally, the proposed electrode was successfully applied to the detection of Ba(2+) ions in real samples as well as in sulfate(II) ions in water.