The interference of vanadium in the titrimetric determination of iron by the tin(II) chloride-mercury(II) chloride-dichromate method

Abstract

The interference of vanadium in the standard tin(II) chloride reduction method for the determination of iron(III) has been investigated and is shown to be caused by the production of vanadium(III) during the reduction step. The vanadium(III) is not re-oxidised on the addition of mercury(II) chloride but is oxidised to vanadium(IV) when the iron(II) is titrated with chromium(VI), yielding a positive error in the titration of the iron(II). Methods of overcoming this interference have been sought but were not entirely successful, and other methods of reduction, e.g., with hydrogen sulphide, are to be preferred for the determination of iron in materials containing vanadium.