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%.

Keywords:

• 8-Hydroxyquinoline sensor
• Potentiometric determination
• Toxic metal ions
• Coated graphite electrode

ACKNOWLEDGMENTS

The author gratefully acknowledges Prof. Dr. Saad S. M. Hassan and Prof. Dr. Mona A. Ahmed for fruitful discussions and kind help.