Physical investigation of the colloidal iron-inulin complex

The iron-inulin complex, which could be applied as a parenteral hematinic agent, is studied by physical techniques. Electron microscopy shows that the complex contains very small particles that are approximately spherical and 10–30 nm in diameter. The examination reveals the presence of an electron-transparent sheath, probably consisting of linked inulin oligomers with M _w ∼ 3000 g mol⁻¹, around the electron-dense, ironcontaining core of the FeOOH particles. FTIR spectroscopy suggests the existence of stronger hydrogen bonds, which are formed in the complexes between FeOOH and oligosaccharides, compared to the hydrogen bond in the initial compounds. A gel filtration technique on a Sephadex column showed conclusively that a large proportion of combined inulin oligomers with M _w ∼ 1500 g mol⁻¹ as secondary fractions are present in complexes. These low-molecular-weight inulin fractions have a significant influence on the complex stability. The text was submitted by the authors in English.