Ferroïne
Ferroïne is the common name for the redox indicator tris(1,10-phenanthroline)iron(II) complex, [Fe(phen)3]2+. In this reduced form the complex is deep red and can be used to signal the endpoint of redox titrations. Its oxidized form, ferriin, has iron in the +3 oxidation state and appears blue.
The complex is formed by complexation of ferrous ions with 1,10-phenanthroline (phen) under mildly acidic conditions,
In a redox titration, ferroïne undergoes oxidation to ferriin, producing a color change from red to blue
Ferroïne is widely employed in redox titrations where the Fe2+/Fe3+ couple is involved, including determinations using
Handling and storage considerations include protecting ferroïne solutions from light and air to minimize degradation. Solutions