Abstract
In dissolution-dynamic nuclear polarization, a hyperpolarized solid is dissolved with a jet of hot solvent. The solution is then transferred to a secondary magnet, where spectra can be recorded with improved sensitivity. In bullet-dynamic nuclear polarization this order is reversed. Pressurized gas is used to rapidly transfer the hyperpolarized solid to the secondary magnet, and the hyperpolarized solid is dissolved only upon arrival. A potential advantage of this approach is that it may avoid excessive dilution and the associated signal loss, in particular for small sample quantities. Previously, we have shown that liquid-state NMR spectra with polarization levels of up to 30 % may be recorded within less than 1 s after the departure of the hyperpolarized solid from the polarizing magnet. The resolution of the recorded spectra however was limited. The system consumed significant amounts of liquid helium, and substantial manual work was required in between experiments to prepare for the next shot. Here, we present a new bullet-DNP (dynamic nuclear polarization) system that addresses these limitations.
Highlights
Dissolution-dynamic nuclear polarization (D-DNP) can provide solutions of hyperpolarized molecules with near-unity spin polarization, corresponding to signal enhancements of > 10 000 in state-of-the-art NMR instruments (ArdenkjærLarsen et al, 2003; Ardenkjaer-Larsen et al, 2015; van Bentum et al, 2016; Ardenkjær-Larsen, 2016; Jannin et al, 2019; Kurzbach and Jannin, 2018; Zhang and Hilty, 2018; Ardenkjær-Larsen, 2019)
The substantial polarization attainable with D-DNP does not in general translate into a corresponding sensitivity gain (Otikovs et al, 2019)
In this paper we present a new system that we designed at our new home, the Karlsruhe Institute of Technology, in order to address these limitations
Summary
Dissolution-dynamic nuclear polarization (D-DNP) can provide solutions of hyperpolarized molecules with near-unity spin polarization, corresponding to signal enhancements of > 10 000 in state-of-the-art NMR instruments (ArdenkjærLarsen et al, 2003; Ardenkjaer-Larsen et al, 2015; van Bentum et al, 2016; Ardenkjær-Larsen, 2016; Jannin et al, 2019; Kurzbach and Jannin, 2018; Zhang and Hilty, 2018; Ardenkjær-Larsen, 2019). The substantial polarization attainable with D-DNP does not in general translate into a corresponding sensitivity gain (Otikovs et al, 2019) This is because the analyte concentration is reduced in the dissolution step and because the throughput of the dissolution-DNP experiment is typically much lower than the repetition rate that can be achieved when recording signals at or near thermal equilibrium. Another approach to reduce the dilution of the analyte in the final solution is to polarize more material to begin with This strategy is costly for precious samples but viable in particular for experiments involving hyperpolarized water (Olsen et al, 2016; Szekely et al, 2018; Novakovic et al, 2020). This magnet system is available commercially from Cryogenic Ltd., UK, and has been installed successfully in several labs (Baudin et al, 2018; Kress et al, 2021)
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