Increase in Signal-to-Noise Ratio of >10,000 Times in Liquid-State NMR

A method for obtaining strongly polarized nuclear spins in solution has been developed. The method uses low temperature, high magnetic field, and dynamic nuclear polarization (DNP) to strongly polarize nuclear spins in the solid state. The solid sample is subsequently dissolved rapidly in a suitable...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2003-09, Vol.100 (18), p.10158-10163
Main Authors: Ardenkjær-Larsen, Jan H., Fridlund, Björn, Gram, Andreas, Hansson, Georg, Hansson, Lennart, Lerche, Mathilde H., Servin, Rolf, Thaning, Mikkel, Golman, Klaes
Format: Article
Language:English
Subjects:
Irradiation
Liquids
Magnetic fields
Magnetic Resonance Spectroscopy - methods
Magnets
Microwaves
Molecules
NMR
Nuclear magnetic resonance
Nuclear spin
Physical Sciences
Signal to noise ratio
Solids
Studies
Supernova remnants
Urea - analysis
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Summary:A method for obtaining strongly polarized nuclear spins in solution has been developed. The method uses low temperature, high magnetic field, and dynamic nuclear polarization (DNP) to strongly polarize nuclear spins in the solid state. The solid sample is subsequently dissolved rapidly in a suitable solvent to create a solution of molecules with hyperpolarized nuclear spins. The polarization is performed in a DNP polarizer, consisting of a superconducting magnet (3.35 T) and a liquid-helium cooled sample space. The sample is irradiated with microwaves at ≈94 GHz. Subsequent to polarization, the sample is dissolved by an injection system inside the DNP magnet. The dissolution process effectively preserves the nuclear polarization. The resulting hyperpolarized liquid sample can be transferred to a high-resolution NMR spectrometer, where an enhanced NMR signal can be acquired, or it may be used as an agent for in vivo imaging or spectroscopy. In this article we describe the use of the method on aqueous solutions of [13C] urea. Polarizations of 37% for13C and 7.8% for15N, respectively, were obtained after the dissolution. These polarizations correspond to an enhancement of 44,400 for13C and 23,500 for15N, respectively, compared with thermal equilibrium at 9.4 T and room temperature. The method can be used generally for signal enhancement and reduction of measurement time in liquid-state NMR and opens up for a variety of in vitro and in vivo applications of DNP-enhanced NMR.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1733835100