Hexacyanoferrate(III) as a mediator in the determination of total iron in potable waters as iron(II)-1,10-phenanthroline at a single-use screen-printed carbon sensor device
Hexacyanoferrate(III) was used as a mediator in the determination of total iron, as iron(II)-1,10-phenanthroline, at a screen-printed carbon sensor device. Pre-reduction of iron(III) at −0.2 V versus Ag/AgCl (1 M KCl) in the presence of hexacyanoferrate(II) and 1,10-phenanthroline (pH 3.5–4.5), to i...
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Veröffentlicht in: | Talanta (Oxford) 2007-01, Vol.71 (1), p.202-207 |
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Sprache: | eng |
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Zusammenfassung: | Hexacyanoferrate(III) was used as a mediator in the determination of total iron, as iron(II)-1,10-phenanthroline, at a screen-printed carbon sensor device. Pre-reduction of iron(III) at −0.2
V versus Ag/AgCl (1
M KCl) in the presence of hexacyanoferrate(II) and 1,10-phenanthroline (pH 3.5–4.5), to iron(II)-1,10-phenanthroline, was complete at the unmodified carbon electrode surface. Total iron was then determined voltammetrically by oxidation of the iron(II)-1,10-phenanthroline at +0.82
V, with a detection limit of 10
μg
l
−1.
In potable waters, iron is present in hydrolysed form, and it was found necessary to change the pH to 2.5–2.7 in order to reduce the iron(III) within 30
s. A voltammetric response was not found at lower pH values owing to the non-formation of the iron(II)-1,10-phenanthroline complex below pH 2.5.
Attempts to incorporate all the relevant reagents (1,10-phenanthroline, potassium hexacyanoferrate(III), potassium hydrogen sulphate, sodium acetate, and potassium chloride) into a modifying coated PVA film were partially successful. The coated electrode behaved very satisfactorily with freshly-prepared iron(II) and iron(III) solutions but with hydrolysed iron, the iron(III) signal was only 85% that of iron(II). |
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ISSN: | 0039-9140 1873-3573 |
DOI: | 10.1016/j.talanta.2006.03.051 |