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

International audience The electrochemical behavior of a Nafion-1,10-phenanthroline-modified carbon paste electrode(CMCPE: Chemically Modified Carbon Paste Elec-trode) immersed in a supporting electrolyte 0.1 mol.L acetate buffer solution (pH4.5) containing iron(II) metal ion has been studied, using cyclic voltammetry, differ-ential-pulse voltammetry and impedance spectroscopy. Optimal analytical parameter s(preconcentration poten-tial and time, pH,electrode rotation) for iron (II) metal ion determination have been established and correlated with the surface morphology of the CMCPE surface, the chemical composition analysis of the surface and the impedance measurements of the CMCPE immersed in the supporting electrolyte. Assuming a simple approach based on a redox polymer-modified electrode, the experimental impedance values were fitted to an equivalent circuit model. It was shown that among various potential sused for iron(II) accumulation in the Nafion-film, the potential of+1.3 V vs. Ag/AgCl/3mol.L KC l allowed a better differential-pulse determination of the examined iron(II) metal ion in the supporting electrolyte. The work was expanded to real applica-tions with the determination of iron(II) metal ion in groundwater samples collected in a village located at the outskirts of Ouagadougou, the Capital of Burkina Faso.