Supercritical fluid chromatography proton nuclear magnetic resonance spectroscopy coupling

The direct on-line coupling between supercritical fluid chromatography (SFC) and supercritical fluid extraction (SFE) and proton high-field nuclear magnetic resonance (NMR) spectroscopy is described, The resolution of the H-1 NMR spectra obtained in SFC-NMR and SFE-NMR coupling experiments under continuous-flow conditions approaches the resolution of conventionally recorded NMR spectra, Due to the supercritical measuring conditions the proton spin-lattice relaxation times T-1 are increased two times at least. A pressure gradient applied for separation purposes results in an highfield shift of H-1 NMR signals, SFC-NMR separations performed with plastifiers, acrylates and vitamins show the broad application range of the technique. SFE-NMR investigations have been performed with natural products as well as with polymers. (C) 1997 Elsevier Science B.V.