A new spectrophotometric method for direct determination of iron (III) in serum

Bakground and purpose of the study: Hydroxypyridin-4-ones, a group of iron chelators have shown promise as potential compounds for the treatment of iron overload by the oral route. Their selectivity and high complex formation constant with iron makes them good candidates for iron determination. In this study the use of N-ethyl-2-methyl-3-hydroxypyridin-4-on (EMHP), a strong and selective ferric chelator, as a new ligand for measurement of mu molar concentrations of iron in aqueous solutions and biological fluids was investigated. This measurement is based on the color reaction of Fe3+ with EMHP. Methods: After mixing serum sample and reagent, and incubating at room temperature, the absorbance of the resulting complex was measured at lambda(max). The effect of analytical variables, such as the amount and the kind of the reagents, pH, ratio of EMHP/Fe (III) and presence of other ions in determination of iron were studied. Results: The results showed that the optimum wavelength for the measurement was 456 nm. Formation of the complex was completed in less than 20 min and it was stable up to 24 hrs. Molar ratio of 6-10 EMHP/Fe (III) and pH = 5 were the optimum conditions for complex formation and determination of Fe (III). The detection limit was 2.5 x 10(-6) M of Fe (III) in serum or plasma. Ions commonly associated with iron did not interfere in the present method. Conclusion: This method which is simple and reproducible was found sensitive for determination of Fe (III) in several real samples at micromolar levels.