Carbon Paste Electrode Modified with 2-Carboxythiophene Benzoylhydrazone as a Potentiometric Sensor for Cu(II)

A new modified carbon paste electrode (CPE) based on a recently synthesized ligand, 2-carboxythiophene benzoyl hydrazone (SHBHy), as a suitable carrier for copper‏(II) ion was described. The electrode exhibits a Nernstian slope of 28.3 mV per decade for Cu (II)‏ ion over a wide concentration range from 3.9 x 10-6-1.0 x 10-3 mol/L. The lower detection limit is 2.5 x 10-6 mol/L Cu(II)‏‏. The electrode has a fast response time (ca. 5-10 s). The proposed sensor shows a fairly good selectivity toward copper(II) ion in comparison to other common cations. The potentiometric responses are independent of the pH of the test solution in the pH range 3.8-5.8. Finally, it was satisfactorily used as an indicator electrode in complexometric titration with EDTA and determination of copper(II) in tap and well water samples.