Monday, September 10, 2018

Continuous hyperpolarization with parahydrogen in a membrane reactor #DNPNMR

Lehmkuhl, Sören, Martin Wiese, Lukas Schubert, Mathias Held, Markus Küppers, Matthias Wessling, and Bernhard Blümich. “Continuous Hyperpolarization with Parahydrogen in a Membrane Reactor.” Journal of Magnetic Resonance 291 (June 2018): 8–13. 

Hyperpolarization methods entail a high potential to boost the sensitivity of NMR. Even though the ‘‘Signal Amplification by Reversible Exchange” (SABRE) approach uses para-enriched hydrogen, p-H2, to repeatedly achieve high polarization levels on target molecules without altering their chemical structure, such studies are often limited to batch experiments in NMR tubes. Alternatively, this work introduces a continuous flow setup including a membrane reactor for the p-H2, supply and consecutive detection in a 1 T NMR spectrometer. Two SABRE substrates pyridine and nicotinamide were hyperpolarized, and more than 1000-fold signal enhancement was found. Our strategy combines low-field NMR spectrometry and a membrane flow reactor. This enables precise control of the experimental conditions such as liquid and gas pressures, and volume flow for ensuring repeatable maximum polarization.