Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 13. Detection of Aqueous Iron by in Situ Complexation with 2, 2’-Bipyridine
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Authors
John Richardson
Aubrey L Dyer
Michael Stegemiller
Imants Zudans
Carl Seliskar
William Heineman
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Type
Journal Article, Professional Journal
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Abstract
A spectroelectrochemical sensor with attenuated total
reflectance at an indium-doped tin oxide (ITO) optically
transparent electrode coated with a thin film of Nafion has
been demonstrated for the determination of aqueous iron
ion. The novelty of this sensor stems from its ability to
take up colorless iron ion (Fe2+) from solution and
complex it with an organic ligand, 2,2′-bipyridine (bipy),
that has been previously loaded in the optically transparent
charge-selective Nafion film coating the electrode. The
resulting complex ion, tris(2,2′-bipyridyl)iron(II),
Fe(bipy)32+, absorbs strongly, making it easily detectable
via optical spectroscopy. Fe(bipy)32+ loaded into the
selective film is oxidized to colorless Fe(bipy)33+, which
gives rise to an absorbance change for quantifying iron.
This paper maps the development of this sensor, from the
spectroelectrochemical characterization of the complex
ion at an ITO optically transparent electrode to an analysis
of the uptake, retention, and optical response of the
complex ion in the Nafion film. Finally, an evaluation of
the uptake of aqueous Fe2+ by the bipy-loaded Nafion film
is reported. These data include preliminary results illustrating
the dependence of the sensor response on
differing concentrations of Fe2+ in solution.