Colorimetric determination of Fe2+/Fe3+

Method:

Colorimetric determination of Fe²⁺/Fe³⁺ after sample dissolution in concentrated HF; the Fe²⁺/Fe³⁺ ratio is preserved using the reversible reaction with V⁵⁺: Fe²⁺ + V⁵⁺ ⇔ Fe³⁺ + V⁴⁺, measurement of the absorption in visible light (Shimadzu UV 1800) caused by a red Fe²⁺-2,2-Bipyridil-complex; determination of total Fe in the same solution via complete reduction of Fe³⁺; small amounts of sample needed (2-50 mg); min. FeO concentration in the sample is 0.5wt% FeO.

Applications:

Determination of Fe²⁺/Fe³⁺- ratio of solid materials such as minerals, glasses and rocks.

Literature:

Schuessler, J.A., Botcharnikov, R.E., Behrens, H., Misiti, V., Freda, C.  (2008): Oxidation state of iron in hydrous phono-tephritic melts, American Mineralogist 93 (10) , pp. 1493-1504