Remarkable Levels of ¹⁵N Polarization Delivered through SABRE into Unlabeled Pyridine, Pyrazine, or Metronidazole Enable Single Scan NMR Quantification at the mM Level

High Resolution Image Download MS PowerPoint Slide While many drugs and metabolites contain nitrogen, harnessing their diagnostic 15 N NMR signature for their characterization is underutilized because of inherent detection difficulties. Here, we demonstrate how precise ultralow field signal amplification by reversible exchange (±0.2 mG) in conjunction para hydrogen and an iridium precatalyst of the form IrCl(COD)(NHC) with the coligand d 9 -benzylamine allows the naturally abundant 15 N NMR signatures of pyridine, pyrazine, metronidazole, and acetonitrile to be readily detected at 9.4 T in single NMR observations through >50% 15 N polarization levels. These signals allow for rapid and precise reagent quantification via a response that varies linearly over the 2–70 mM concentration range.