A NOVEL 8-HYDROXYQUINOLINE PVC COATED GRAPHITE SENSOR FOR POTENTIOMETRIC DETERMINATION OF SOME METAL IONS

ABSTRACT A novel potentiometric 8-hydroxyquinoline PVC coated graphite sensor incorporating 8-hydroxyquinoline (oxine)–tetraphenylborate (TPB) ion pair as an electroactive material and dioctylphthalate (DOP) as a solvent mediator is described and electrochemically evaluated. The proposed sensor exhibits fast Nernstian response for 8-hydroxyquinoline over the concentration range 10−6–10−1 mol L−1 with a cationic calibration slope of 59.0 ± 0.5 mV/concentration decade and a detection limit of 4 × 10−7 mol L−1 (0.05 ppm). Interferences from common inorganic cations are negligible. The sensor is successfully used for monitoring titration of some metal ions (e.g., Cu2+, , Cd2+, Ca2+, , Co2+, Ni2+, Zn2+, Th4+, and Pb2+) with 8-hydroxyquinoline titrant at suitable pH values. Some metal ions (e.g., Cu2+) are determined in presence of many common metal ions without interference. The average recoveries of the tested metal ions ranged from 95–98 ± 1% and a mean standard deviation is 1.8%.