Electrochemical determination of iron(II) at a Nafion-1,10- phenanthroline-modified carbon paste electrode:Assessing the correlation between preconcentration potential, surface morphology and impedancemeasurements

Author(s): Abdoulkadri AyoubaMahamane, Boubié Guel, Paul-Louis Fabre

The electrochemicalbehaviorof aNafion- 1,10-phenanthroline-modified carbon paste electrode (CMCPE: ChemicallyModified Carbon Paste Electrode) immersed in a supporting electrolyte 0.1mol.L-1 acetatebuffer solution(pH4.5) containingiron(II)metal ion has been studied, using cyclic voltammetry, differential- pulse voltammetryand impedance spectroscopy. Optimal analyticalparameters (preconcentration potential and time, pH, electrode rotation) for iron(II)metal ion determination have been established and correlated with the surfacemorphology of theCMCPE surface, the chemical composition analysis of the surface and the impedancemeasurementsof theCMCPEimmersed in the supporting electrolyte.Assuming a simple approach based on a redox polymer-modified electrode the experimental impedance values were fitted to an equivalent circuitmodel. Itwas shownthat amongvarious potentials used for iron(II) accumulation in the Nafion-film, thepotentialof+1.3Vvs.Ag/AgCl/3mol. L-1KCl allowed a better differential-pulse determination of the examined iron(II)metal ionin the supporting electrolyte. Thework was expanded to real applications with the determination of iron(II) metal ion in groundwater samples collected in a village located at the outskirts ofOuagadougou, theCapital ofBurkina Faso.

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