Theis, T., et al., Microtesla SABRE enables 10% nitrogen-15 nuclear spin polarization. J Am Chem Soc, 2015. 137(4): p. 1404-7.
http://www.ncbi.nlm.nih.gov/pubmed/25583142
Parahydrogen is demonstrated to efficiently transfer its nuclear spin hyperpolarization to nitrogen-15 in pyridine and nicotinamide (vitamin B(3) amide) by conducting “signal amplification by reversible exchange” (SABRE) at microtesla fields within a magnetic shield. Following transfer of the sample from the magnetic shield chamber to a conventional NMR spectrometer, the (15)N NMR signals for these molecules are enhanced by approximately 30,000- and approximately 20,000-fold at 9.4 T, corresponding to approximately 10% and approximately 7% nuclear spin polarization, respectively. This method, dubbed “SABRE in shield enables alignment transfer to heteronuclei” or “SABRE-SHEATH”, promises to be a simple, cost-effective way to hyperpolarize heteronuclei. It may be particularly useful for in vivo applications because of longer hyperpolarization lifetimes, lack of background signal, and facile chemical-shift discrimination of different species.