C-13 NMR USED AS CHROMATOGRAPHIC DETECTOR

The DNP technique involving the intermolecular transfer of spin polarization from a silica phase-immobilized nitroxide to a liquid analyte flowing over the silica-nitronide surface is developed to achieve the sensitivity increases needed to detect the weak 13C NMR signals from HPLC. The limitation suffered by 13C NMR in the signal-to-noise ratio is accomplished by DNP by transferring energy from unpaired electrons in immobilized nitroxide groups to nuclei in the analyte. With further improvements in the signal-to-noise ratio in the DNP, this approach can be extended to other nuclei such as 15N, 29Si, and 31P, respectively.