ONLINE COUPLING OF SUPERCRITICAL-FLUID CHROMATOGRAPHY AND PROTON HIGH-FIELD NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

The direct on-line coupling of supercritical fluid chromatography and proton high-field nuclear magnetic resonance spectroscopy is demonstra ted. For this purpose, a specially designed pressure-proof continuous- flow probe head has been developed, from which a signal line width of 1.5 Hz can be obtained in the supercritical state. A separation of pht halates is carried out under supercritical conditions with carbon diox ide as eluent and is monitored on-line with H-1 NRIR on a 400-MHz NMR instrument. All the components can be identified from their NMR spectr a. The advantage of carbon dioxide as eluent is that the whole spectra l range of the H-1 NMR spectra can be observed and no solvent suppress ion techniques are necessary to obtain the MMR spectre. Continuous-flo w H-1 NMR spectra acquired under supercritical conditions are of the s ame quality as those recorded in liquids.