Quantitative Trace Analysis of Complex Mixtures Using SABRE Hyperpolarization

Signal amplification by reversible exchange (SABRE) is an emerging nuclear spin hyperpolarization technique that strongly enhances NMR signals of small molecules in solution. However, such signal enhancements have never been exploited for concentration determination, as the efficiency of SABRE can strongly vary between different substrates or even between nuclear spins in the same molecule. The first application of SABRE for the quantitative analysis of a complex mixture is now reported. Despite the inherent complexity of the system under investigation, which involves thousands of competing binding equilibria, analytes at concentrations in the low micromolar range could be quantified from single‐scan SABRE spectra using a standard‐addition approach. Quantitative trace analysis: Nuclear spin hyperpolarization of small molecules in complex mixtures is achieved by signal amplification by reversible exchange (SABRE). The resulting signal enhancements allow quantification of compounds present at low micromolar concentrations in a few single‐scan NMR experiments.