Dipolar cross-relaxation modulates signal amplitudes in the (1)H NMR spectrum of hyperpolarized [(13)C]formate

J Magn Reson. 2007 Dec;189(2):280-5. doi: 10.1016/j.jmr.2007.09.011. Epub 2007 Sep 20.


The asymmetry in the doublet of a spin coupled to hyperpolarized (13)C has been used previously to measure the initial polarization of (13)C. We tested the hypothesis that a single observation of the (1)H NMR spectrum of hyperpolarized (13)C formate monitors (13)C polarization. Depending on the microwave frequency during the polarization process, in-phase or out-of-phase doublets were observed in the (1)H NMR spectrum. Even in this simple two-spin system, (13)C polarization was not reflected in the relative area of the J(CH) doublet components due to strong heteronuclear cross-relaxation. The Solomon equations were used to model the proton signal as a function of time after polarization and to estimate (13)C polarization from the (1)H NMR spectra.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Algorithms*
  • Carbon Isotopes
  • Carbon Radioisotopes
  • Computer Simulation
  • Formates / chemistry*
  • Magnetic Resonance Spectroscopy / methods*
  • Models, Chemical*
  • Models, Molecular*
  • Protons


  • Carbon Isotopes
  • Carbon Radioisotopes
  • Formates
  • Protons
  • formic acid