SUPERCRITICAL-FLUID CHROMATOGRAPHY AND EXTRACTION OF FE(III) WITH HYDROXAMIC ACIDS

Representative aliphatic and aromatic mono-hydroxamic acids are shown to be separable by supercritical fluid chromatography (SFC) using meth anol modified CO2 on a diol column. Evidence for ligand contamination by Fe(III) from the SFC system is provided, as the ligands are detecte d as Fe(III) chelates at 420 nm. The ligands and chelates studied were octanohydroxamic acid (OHA), Fe(OHA)(3), benzohydroxamic acid (BHA), Fe(BHA)(3), heptanohydroxamic acid (HHA), Fe(HHA)(3), and a newly synt hesised hydroxamic acid, perfluorooctanohydroxamic acid (PFOHA). When the ligands were examined using unmodified supercritical CO2 (SF-CO2) for their ability to extract Fe(III) from solid supports by supercriti cal fluid extraction (SEE), the fluorinated hydroxamic acid showed enh anced performance and solubility.