¹³C NMR spectroscopy as a tool for the in situ characterisation of iron-supplementing preparations

Abstract

(13)C NMR spectroscopy provides insight into the chemistry of carbohydrate-based ferric preparations. Specifically, it reveals whether oxygen atoms of the carbohydrate are directly bonded to the preparations' ferric centres or whether more distant interactions are present. After having validated the method by investigating the ferric solutions of low-molecular complexes as well as polynuclear ferric samples, it is demonstrated that common constituents of medically used ferric preparations such as sucrose and other glucose-based saccharides do not support ferric carbohydrate chelates. Instead, these carbohydrates reside outside the NMR-spectroscopically 'blinded' region about the ferric centres and experience the so-called Evans effect that can be used to measure the magnetic moment of the solutions. As a result, an easily accessible physicochemical parameter is provided to characterise commercial iron(III) preparations, namely the samples' magnetism in terms of the in situ-measured spin-normalised effective Bohr magneton number μ(eff)(2)/35. The procedure can, moreover, be combined with a facile NMR-spectroscopic iron assay.

Keywords: Carbohydrate-supported ferric nanoparticles; Evans method; Ferric preparations; Iron sucrose; Iron sucrose similars; Magnetic susceptibility.