Extract-photometric determination of iron with 2-indolehydroxamic acid

A new extract-photometric method is proposed for determining trace amounts of Fe3+ based on the formation of a coloured complex with 2-indolehydroxamic acid (2-IHA), that can be extracted into a solution of trioctylmethylammonium chloride solution in toluene. Beer's law was obeyed between 0.06 μg/g and 1.25 μg/g (minimum error range) of iron in the aqueous phase, with a relative error (p=0.05) of ±0.86%. Molar absortivity at 455 nm was 6500 l mol−1 cm−1. The method was applied to the determination of iron in various samples: commercial pharmaceutical nutritional preparations, wine and standard samples of Portland cement and magnesite.