Chelating agent differences in ferrous iron determinations

Publisher Website
Google Scholar
Abstract
Experiments were conducted to test the ability of ferrous iron (Fe2+) chelating agents to discriminate between Fe2+ and ferric iron (Fe3+), to determine ranges of Fe2+ detection in reactions, to determine interactions of chelating agents with phosphorus (P) which is common in plant tissue, and to evaluate some of the complexities of methodology for Fe2+ determinations. PDTS [ferrozine; 3‐(2 pyridyl)‐5,6‐bis (4‐phenyl‐sulfonic acid)‐l,2,4‐triazine] reacted with only small amounts of Fe3+, had a fairly wide range of Fe2+ detection (0–200 μg), P did not interfere with the reaction, and methodology was relatively simple. TPTZ [2,4,6‐tripyridyl‐s‐triazine] was very specific for Fe2+, did not react with Fe3+, had a relatively narrow range of Fe2+ detection (0–40 μg), P did not interfere with the reaction, and methodology was relatively simple. BPDS [4,7‐diphenyl 1.10‐phenanthrolinedisulfonic acid] reacted with a small amount of Fe3+, had a fairly wide range of Fe2+ detection (40–200 μg), did not react with low levels of Fe2+ (3+, had a wide range of Fe2+ detection (0–200 μg), P did not interfere with the reaction, and methodology was relatively simple. BDTPS [2,4‐bis(5,6‐diphenyl‐1,2,4‐triazine‐3‐yl)‐pyridinetetrasulfonic acid], BPT [4,7‐diphenyl‐1,10‐phenanthroline], and PDT [3‐(2pyridyl)‐5,6‐diphenly‐1,2,4‐triazine] were considered, but the literature indicated that P interferred with BDTPS and BPT reactions, citrate interferred with the BPT reactions, and the methodologies for PDT and BPT were relatively complex (required special separations and extractions). PDTS was the best of the chelating agents tested for Fe2+ determinations. OPh plus hydroxylamine (OPhH) was the best of the chelating agents for the determination of total Fe.