title: Dipolar cross-relaxation modulates signal amplitudes in the (1)H NMR spectrum of hyperpolarized [(13)C]formate.
abstract: 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.
authors.affiliation: Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, TX 75390-8568, USA. matthew.merritt@utsouthwestern.edu
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Merritt
authors.forename: Crystal
authors.initials: C
authors.lastname: Harrison
authors.forename: William
authors.initials: W
authors.lastname: Mander
authors.forename: Craig R
authors.initials: CR
authors.lastname: Malloy
authors.forename: A Dean
authors.initials: AD
authors.lastname: Sherry
mesh_terms: D000465:Algorithms; D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D003198:Computer Simulation; D005561:Formates / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D011522:Protons
chemical_list: D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D005561:Formates; D011522:Protons; C030544:formic acid