The application of ion chromatographic method for bioavailability and stability test of iron preparations

Postabsorptive serum iron level was determined after oral administration of the compounds to human. In serum and whole blood, Fe3+ was measured by ion chromatography (IC) using a pyridine-2,6-dicarboxylic acid (PDCA) as an el uent The serum sample solutions were pretreated with N HCl and 50% TCA. The whole blood sample solutions were treated with 3 N HCl for 30 min at 125 d egrees C. The limit of detection (LOD) of the IC technique is 0.2 mu M for Fe2+ and 0.1 mu M for Fe3+ The area under concentration (AUC) can be obtain ed by the above analytical condition. In addition, to compare the stability of Fe2+ to that of Fe in pharmaceutical preparations, accelerated stabilit y test was carried out. After storing the samples under 40 degrees C, 75%RH in light-resistant container for various time intervals, the contents of i ron of different valencies were determined separately by the IC technique a nd the change and/or the interchange of among those iron species in prepara tions was investigated. Iron raw materials are stable, but Fe2+ in Fe3+ sou rce materials was slightly converted to Fe3+ by oxidation. Fe2+ in Fe3+ sou rce raw materials and Fe3+ in Fe2+ raw materials are determined as impuriti es. Therefore, IC technique is found to be an appropriate method for compar ative evaluation of dissimilar bioavailability of Fe2+ and Fe3+, stability of Fe2+ and Fe3+ raw materials and preparations.