SABRE hyperpolarization. Parahydrogen (pH2), Ir-catalyst, cosubstrate (1-methyl-1,2,3-triazole, mtz), and analytes are involved in a reversible binding equilibrium. During the lifetime of the complex, the spin order of pH2 is converted to nuclear hyperpolarization in analytes.[7] Polarization transfer is conducted at low field outside the NMR magnet, after which the sample is inserted into the spectrometer for detection. An excess of mtz is needed for sub-millimolar SABRE to restore catalyst activity at low analyte concentrations.[13] nitrogenous heteroaromatics,[7,8,9a,b] examples of sulfur heter- oaromatic compounds,[10] nitriles,[11a] Schiff bases[11b] and diazirines[11c] have been reported. Several such SABRE- active moieties appear in the structures of drugs,[11d,12] odor- ants[9b] and metabolites,[9a] giving rise to an interest in devising new analytical approaches for their detection. Furthermore, [*] Xx. X. Reile, R. L. E. G. Aspers, Xx. X. X. Xxxxxxx, Prof. F. P. J. T. Xxxxxx, Xx. X. Tessari Institute for Molecules and Materials, Radboud University Xxxxxxxxxxxxxx 000, 0000XX Xxxxxxxx (Xxx Xxxxxxxxxxx) E-mail: x.xxxxxxx@xxxxxxx.xx.xx J.-M. Tyburn Bruker BioSpin GmbH Silberstreifen, Rheinstetten (Germany) Xx. X. X. Xxxxx Bruker Biospin Corp. Billerica, MA 01821 (USA) Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: xxxxx://xxx.xxx/10.1002/anie.201703577. although the original SABRE methods did not maintain the quantitative abilities of NMR spectroscopy, a general approach to analytical SABRE was recently developed and used for quantification of sub-micromolar analytes (Scheme 1).[13] Figure 1 depicts the aromatic region of a single-scan SABRE spectrum of a mixture of six dilute analytes. The molecules 1–6 and similar analogues occur as low-micromolar concentration flavor components in food extracts,[14] but spectral elucidation of their mixtures is complicated if based on 1D spectra alone. Herein, we overcome this challenge with a new method that combines SABRE with DOSY to resolve the signals of analytes 1–6 at low-micromolar concentrations. 9174 T 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Angew. Chem. Int. Ed. 2017, 56, 9174 –9177 Figure 1. Region of interest of SABRE spectrum. Concentrations of analytes are 25 mm (1), 10 mm (2–5), and 5 mm (6). Catalyst-mtz background signals are highlighted with (*). Note that SABRE enhan- ces each signal by a factor that is not directly related to analyte concentr...
