Preliminary studies of iron speciation (Fe2+ and Fe3+) in peat samples using polarography

Current-sampled (tast) polarography was used in the determination of the two iron oxidation states Fe2+ and Fe3+ in peat samples. The iron couple was reversible in the 0.1 mol L-1 citrate-supporting electrolyte used. The total iron concentration in the samples was determined by differential pulse polarography. Sample decomposition was done in a nitrogen atmosphere by hydrofluoric acid and sulfuric acid. The accuracy of the determinations was verified by spiking experiments and analyzing in-house standards (Geological Survey of Finland) RS 31 (Rapakivi granite), RS 71 (Diabase) and certified reference material PCC-1 (Peridotite, U.S. Geological Survey). The method, developed for this purpose, proved to be reasonably accurate.