SEPARATION AND IDENTIFICATION OF VITAMIN-A ACETATE ISOMERS BY SUPERCRITICAL-FLUID-CHROMATOGRAPHY H-1-NMR COUPLING

Unlike HPLC-NMR coupling, the combination of supercritical fluid chrom atography (SFC) with NMR spectroscopy is not yet a routine method, but the feasibility of this coupling technique has already been demonstra ted with synthetic mixtures. In this paper the first real life applica tion is presented and the potential of this new method is shown. A mix ture of five cis/trans isomers of vitamin A acetate is separated by SF C using supercritical CO2 as eluent. Therefore no solvent signal suppr ession is necessary and the unrestricted observation of the whole spec tral range is possible, contrary to the HPLC separation in n-heptane, where in the aliphatic region almost 2 ppm of the H-1 NMR spectrum are affected by the suppression technique.