Selective NMR detection of individual reaction components hyperpolarised by reversible exchange with para-hydrogen.

NMR spectroscopy can sometimes be hampered by two inherent weaknesses: low sensitivity and overlap of signals in complex mixtures. Hyperpolarisation techniques using para-hydrogen (including the method known as SABRE) can overcome this sensitivity problem, but cannot circumvent spectral overlap. Conversely, a recently described selective excitation technique (known as DREAMTIME) can overcome overlap in mixtures, but suffers from a decrease in sensitivity. Here we demonstrate the combination of these two methods in a single approach termed SABRE-DREAM, to selectively provide hyperpolarised signals of user-specified components of a chemical reaction, where otherwise overlapping 1 H signals would hinder reaction monitoring or analysis.