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Colorimetric Determination of Iron of Mixed Valency by Orthophenanthroline
Author(s) -
Murti G. S. R. Krishna,
Volk V. V.,
Jackson M. L.
Publication year - 1966
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/sssaj1966.03615995003000050037x
Subject(s) - valency , chemistry , hydroxylamine hydrochloride , complex formation , hydroxylamine , sodium citrate , inorganic chemistry , nuclear chemistry , organic chemistry , medicine , philosophy , linguistics , pathology
A colorimetric method for the determination of Fe in a mixed Fe 3+ and Fe 2+ valency system has been proposed. Complete reduction of Fe 3+ to Fe 2+ , which was essential for the formation of a stable colored complex with orthophenanthroline, was obtained when the iron solution, buffered at pH 3.5 with sodium acetate, was heated for 1 hr at 65C with 5% hydroxylamine hydrochloride. This reduction procedure was found to be suitable even for solutions at a higher pH where iron was present either as Fe 3+ or as a hydroxylated complex. The organe color complex was found to be stable at pH values 2 to 9 for at least 20 hr and no interference of citrate ion was observed in the stability or the formation of the color.