Ferrous iron in iron sucrose injection – Rapid and reliable determination by thermometric titration

Iron sucrose injections are used in the treatment of iron deficiency anemia. They contain a mixture of ferric iron (Fe3+) and ferrous iron (Fe2+). Ferrous iron content may be determined by subtracting the ferric iron content from the total iron
content. Yet, this increases the measurement error due to error propagation. Alternative determination of iron(II) with cerium(IV) by potentiometric titration may be hampered, as the equivalence point cannot be determined unequivocally.

Determination by thermometric titration is a more robust and therefore more reliable alternative, as this method is unaffected by the sample matrix. Here, the end point of the titration is indicated by a fast responding thermometric sensor. Endpoint detection is further improved by spiking the sample with 0.2% ammonium iron(II) sulfate (FAS) improved, increasing the reliability of the determination. Compared to potentiometric titration, thermometric titration is
faster and more convenient (no sensor maintenance required). One determination takes about 2 – 3 minutes.