Relayed hyperpolarization for zero-field nuclear magnetic resonance

Abstract

Zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) is a rapidly developing form of spectroscopy that provides rich spectroscopic information in the absence of large magnetic fields. However, signal acquisition still requires a mechanism for generating a bulk magnetic moment for detection, and the currently used methods only apply to a limited pool of chemicals or come at prohibitively high cost. We demonstrate that the parahydrogen-based SABRE (signal amplification by reversible exchange)–Relay method can be used as a more general means of generating hyperpolarized analytes for ZULF NMR by observing zero-field J -spectra of [ 13 C]-methanol, [1- 13 C]-ethanol, and [2- 13 C]-ethanol in both 13 C-isotopically enriched and natural abundance samples. We explore the magnetic field dependence of the SABRE-Relay efficiency and show the existence of a second maximum at 19.0 ± 0.3 mT. Despite presence of water, SABRE-Relay is used to hyperpolarize ethanol extracted from a store-bought sample of vodka (% P H ~ 0.1%).