Single-Scan Multidimensional NMR Analysis of Mixtures at Sub-Millimolar Concentrations by using SABRE Hyperpolarization

Signal amplification by reversible exchange (SABRE) is a promising method to increase the sensitivity of nuclear magnetic resonance (NMR) experiments. However, SABRE-enhanced H-1 NMR signals are short lived, and SABRE is often used to record 1D NMR spectra only. When the sample of interest is a complex mixture, this results in severe overlaps for H-1 spectra. In addition, the use of a co-substrate, whose signals may obscure the H-1 spectra, is currently the most efficient way to lower the detection limit of SABRE experiments. Here, we describe an approach to obtain clean, SABRE-hyperpolarized 2D H-1 NMR spectra of mixtures of small molecules at sub-millimolar concentrations in a single scan. The method relies on the use of para-hydrogen together with a deuterated co-substrate for hyperpolarization and ultrafast 2D NMR for acquisition. It is applicable to all substrates that can be polarized with SABRE.