In situ Hyperpolarization Enables Benchtop NMR of Heteronuclei at Natural Isotopic Abundance

Without employing isotopic labeling, we demonstrate generation of 15N and 13C NMR signals for molecules containing -NH2 motifs using benchtop NMR spectrometers (1-1.4 T). Specifically, high-SNR detection of ammonia, 4-aminopyridine, benzylamine, and phenethylamine dissolved in methanol or dichloromethane, is demonstrated after only 10 seconds of parahydrogen bubbling using signal amplification by reversible exchange (SABRE) and applying a pulse sequence based on spin-lock induced crossing (SLIC). Optimization of the sequence parameters allowed achieving up to 12 % 15N and 0.4 % 13C polarization in situ without need for the sample transfer typically employed in other hyperpolarization methods. The provided methodology can find applications for detecting mM concentrated solution-state chemicals in various samples relevant to industry and research.