Simultaneous speciation analysis of Fe(II) and Fe(III) in mineral samples by using capillary electrophoresis

Capillary electrophoresis is used as a means of cation separation for cationic speciation analysis. Acceptable separation of ferrous and ferric iron was achieved by using a mixed complexing agent run buffer which gave stable species in solution. These iron species, and total iron, were determined simultaneously in certified reference materials with a single digestion step. A variety of digestion techniques were compared, primarily for their non-oxidative capabilities in order to preserve the oxidation state of iron in the mineral samples. The most favorable recoveries resulted from a continuous flow nitrogen purge technique. Total iron levels obtained from the CE method were compared with those determined by two spectroscopic techniques, with similar results obtained using the different instrumental methods.