A novel 8-hydroxyquinoline PVC coated graphite sensor for potentiometric determination of some metal ions

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 +/- 0.5mV/concentration decade and a detection limit of 4 x 10(-7) mol L-1 (0.05ppm). Interferences from common inorganic cations are negligible. The sensor is successfully used for monitoring titration of some metal ions (e.g., Cu2+, UO22+, Cd2+, Ca2+, VO+, 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%.