High-throughput continuous-flow system for SABRE hyperpolarization.

Vladimir V Zhivonitko,Clara Sanchez-Perez,Petr Štěpánek,Ville-Veikko Telkki,Anu M Kantola

doi:10.1016/j.jmr.2019.01.003

Abstract

Signal Amplification By Reversible Exchange (SABRE) is a versatile method for hyperpolarizing small organic molecules that helps to overcome the inherent low signal-to-noise ratio of nuclear magnetic resonance (NMR) measurements. It offers orders of magnitude enhanced signal strength, but the obtained nuclear polarization usually rapidly relaxes, requiring a quick transport of the sample to the spectrometer. Here we report a new design of a polarizing system, which can be used to prepare a continuous flow of SABRE-hyperpolarized sample with a considerable throughput of several millilitres per second and a rapid delivery into an NMR instrument. The polarizer performance under different conditions such as flow rate of the hydrogen or liquid sample is tested by measuring a series of NMR spectra and magnetic resonance images (MRI) of hyperpolarized pyridine in methanol. Results show a capability to continuously produce sample with dramatically enhanced signal over two orders of magnitude. The constant supply of hyperpolarized sample can be exploited, e.g., in experiments requiring multiple repetitions, such as 2D- and 3D-NMR or MRI measurements, and also naturally allows measurements of flow maps, including systems with high flow rates, for which the level of achievable thermal polarization might not be usable any more. In addition, the experiments can be viably carried out in a non-deuterated solvent, due to the effective suppression of the thermal polarization by the fast sample flow. The presented system opens the possibilities for SABRE experiments requiring a long-term, stable and high level of nuclear polarization.

Highlights

Nuclear magnetic resonance (NMR) is an invaluable method finding applications in many fields ranging from physics through chemistry to biological studies
All numerical NMR data are reported as signal enhancements of NMR peaks with respect to the signal of fully thermally polarized sample in 300 MHz (7 T) magnet
A rather high volume of sample required in the current iteration of the instrument can be offset by using a nondeuterated solvent, the signal of which is efficiently suppressed via the insufficient thermal polarization during the flow

Summary

Introduction

Nuclear magnetic resonance (NMR) is an invaluable method finding applications in many fields ranging from physics through chemistry to biological studies. It is a very versatile technique, offering ways for elucidation of complex molecular structures [1], measuring dynamic molecular processes [2] or investigating porosity of materials [3]. It forms a basis of magnetic resonance imaging (MRI), an indispensable tool in contemporary medical diagnosis and a generally versatile method for noninvasive visualization of spatial density of atomic nuclei.

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Conclusion