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Issue 29, 2017
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Dissolution DNP using trityl radicals at 7 T field

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Dissolution DNP has become an important method to generate highly polarized substrates such as pyruvic acid for in vivo imaging and localized spectroscopy. In a quest to further increase the polarization levels, which is important for in vivo MRI employing 13C detection, we describe the design and implementation of a new DNP polarizer that is suitable for dissolution operation at 7 T static magnetic field and a temperature of 1.4 K. We describe all important sample preparation steps and experimental details necessary to optimize trityl based samples for use in our polarizer at this higher field. In [1-13C]-pyruvic acid polarization levels of about 56% are achieved, compared to typical polarization levels of about 35–45% at a standard field of 3.4 T. At the same time, the polarization build-up time increases significantly from about 670 s at 3.4 T to around 1300–1900 s at 7 T, depending on the trityl derivate used. We also investigate the effect of adding trace amounts of Gd3+ to the samples. While one trityl compound does not exhibit any benefit, the other profits significantly, boosting achievable polarization by 6%.

Graphical abstract: Dissolution DNP using trityl radicals at 7 T field

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The article was received on 30 May 2017, accepted on 23 Jun 2017 and first published on 23 Jun 2017

Article type: Paper
DOI: 10.1039/C7CP03633G
Citation: Phys. Chem. Chem. Phys., 2017,19, 19196-19204
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    Dissolution DNP using trityl radicals at 7 T field

    F. Jähnig, G. Kwiatkowski, A. Däpp, A. Hunkeler, B. H. Meier, S. Kozerke and M. Ernst, Phys. Chem. Chem. Phys., 2017, 19, 19196
    DOI: 10.1039/C7CP03633G

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