Quantitative Trace Analysis of Dilute Mixtures Using a Benchtop NMR System with SABRE Hyperpolarization

Despite their modest sensitivity, benchtop NMR spectrometers have recently attracted a great deal of attention, because of their low cost, high portability, and robustness. A solution to the sensitivity limitation of benchtop spectrometers is offered by nuclear spin hyperpolarization, by which large NMR signal enhancements can be realized. Signal Amplification By Reversible Exchange (SABRE) is one-such hyperpolarization technique, which utilizes hydrogen enriched in the <i>para</i> spin-isomer (<i>p</i>H₂). However, the application of SABRE with benchtop NMR has so far largely been restricted to sample concentrations in the millimolar range. In this work, we present SABRE hyperpolarization of a mixture at micromolar concentrations, measured on a 1 T benchtop spectrometer. The observed linear dependence between hyperpolarized signals and concentration demonstrates the stability of our approach, which allows quantification in the micromolar range.