New Coated Graphite Potentiometric Sensor for Selective Determination of Copper (II) Ions

A highly selective copper (II) coated graphite sensor was prepared by 1,13-bis(8-quinolyl)- 1,4,7,10,13-pentaoxatridecane (kryptofix 5) as a supramolecule ionophore into plasticized polyvinyl chloride (PVC) membrane. The best response characteristic was observed using the membrane composition of PVC = 30.0 mg, dioctyl sebacate (DOS) = 63.5 mg, palmitic acid (PA) = 3.0 mg and kryptofix 5 = 3.5 mg. The sensor exhibits a nernstian slope (30.0±0.2 mV/ decade) in a wide linear concentration range of 1.0×10-5 to 1.0×10-1 M with detection limit of 8.7×10-6 M. The electrode has a fast response time of 15 s with a satisfactory reproducibility and relatively long life time of about 16 weeks without significant drift in potential. The sensor operates in the wide pH range of 2.0-10.0. This sensor reveals a good selectivity towards Cu2+ ion over a wide range of alkali, transition and heavy metal cations. The electrode was used as an indicator electrode for potentiometric titration of Cu2+ using EDTA solutions. The proposed sensor was applied for the direct determination of Cu2+ cation and the results were compared with those obtained from atomic absorption spectrometric analysis and were found in good agreement. Also this sensor was successfully used for determination of copper (II) in real samples