Nuclei with long T 1s are optimal targets for dynamic nuclear polarization (DNP). Therefore, most of the agents used in metabolic imaging and spectroscopy studies are based on carboxylic acid moieties that lack protons, a strong source of dipolar relaxation. Metabolic flux information encoded into spectra of small molecule metabolites in the form of the 13C isotopomer data cannot be accessed using standard 13C hyperpolarization methods because protonated carbons relax too quickly through T 1 dipolar relaxation. It is shown here that the longitudinal mixing sequence FLOPSY-8 can be used to transfer polarization from a long T 1 storage nucleus to adjacent protonated carbons so that they may be detected with high sensitivity. We demonstrate that FLOPSY-8 allows a direct readout of isotopomer populations in butyrate and glutamate in vitro.
- Polarization transfer
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Condensed Matter Physics