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Determination of Fe(III) and Fe(II) in Oxalate Extracts of Sediment
Author(s) -
Phillips Elizabeth J. P.,
Lovley Derek R.
Publication year - 1987
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1987.03615995005100040021x
Subject(s) - ammonium oxalate , oxalate , chemistry , hydroxylamine hydrochloride , extraction (chemistry) , ammonium , nuclear chemistry , sediment , hydroxylamine , inorganic chemistry , chromatography , geology , biochemistry , organic chemistry , paleontology
A method was developed to determine the concentrations of oxalate‐extractable Fe(III) and Fe(II) in sediments. Sediment was extracted in acid ammonium oxalate under N 2 . Iron(II) in the extract was determined with ferrozine. Iron(III) in the extract was reduced with hydroxylamine‐hydrochloride, and total Fe in the extract was determined with ferrozine. Oxalate‐extractable Fe(III) was calculated as the difference between Fe(II) and total Fe in the extract. Iron(II) was not oxidized, and Fe(III) was not reduced during the extraction. For an accurate estimate of oxalate‐extractable Fe(III), fresh samples had to be analyzed, because air‐drying or freeze‐drying the samples oxidized Fe(II) to oxalate‐extractable Fe(III). With a minimal increase in analytical effort, the method yields far more information on Fe geochemistry than the standard aerobic oxalate extraction method.