Volumetric determination of iron (III) with hydroxylamine as a reducing agent

Andhra University
Fresenius Journal of Analytical Chemistry 10/1959; 165(6):432-436. DOI: 10.1007/BF00462146


A new volumetric method has now been developed for the determination of iron(III) through reduction to iron(II) with excess of hydroxylamine. The reduction is completed at the temperature of the boiling water bath in 10 min, keeping the acidity at 0.2–0.5 N sulphuric acid. The mixture is cooled and treated with enough 1 1 sulphuric acid to bring up the acidity to 6 N. It is then titrated with a standard solution of sodium vanadate, using N-phenyl anthranilic acid as inside indicator. Diphenyl benzidine, barium diphenyl sulphonate, or 1,10-phenanthroline cannot be used as indicators in this titration, because of the interference of the unreacted hydroxylamine.The method has been found to be very precise, and convenient. It has also the advantage that it is subject to fewer interferences than the existing methods.

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