Gravimetric determination of iron by precipitation as the [(C4H9)4N]3[Fe(SCN)6] ion pair

The Fe(III)-SCN– complex forms a water-insoluble ionic association compound with the tetrabutylammonium ion. This compound shows a definite stoicheiometric composition, [(C4H9)4N]3[Fe(SCN)6], under the optimum conditions. The compound may therefore be used for the gravimetric determination of iron. The gravimetric factor, 0.0495, is more favourable than others reported elsewhere, permitting the determination of at least 0.60 mg of iron with an error in the order of 0.6–0.7%.