Coulometric determination of serum iron

The iron in 500 μl of serum is determined by a coulometric titration developed for ferroin. The titration step is preceded by chloroform extraction from a protein-free filtrate of serum iron as ferroin perchlorate. Evaporation of chloroform in the presence of an acetate buffer of pH 4.6 causes the ferroin perchlorate to back-extract into the aqueous layer. The ferroin is introduced into a titration cell and titrated with electrogenerated cerium(IV), a modified amperometric end-point detection system being used.