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Updated: May 16, 2026

Dissolution Dynamic Nuclear Polarization Instrumentation for Real-time Enzymatic Reaction Rate Measurements by NMR
Published on: February 23, 2016
The efficiency of DPPH as a polarising agent for DNP-NMR spectroscopy
Lloyd Lumata1, Matthew Merritt, Chalermchai Khemtong
1Advanced Imaging Research Center, University of Texas, Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390 USA. ; Tel: +1-214-645-2750.
Abstract:
The free radical 2,2-diphenyl-1-pycrylhydrazyl (DPPH) was tested as a polarising agent for fast dissolution dynamic nuclear polarisation (DNP) NMR spectroscopy. DPPH was found to be reasonably soluble in sulfolane and the optimum concentration for DNP is 20-40 mM depending upon whether short polarisation times or the maximum signal intensity is needed. W-band ESR measurements revealed that the ESR linewidth D of DPPH is intermediate between that of BDPA and 4-oxo-TEMPO. Several thousand-fold NMR signal enhancements in the liquid-state were achieved for (13)C, (15)N, (89)Y, and (109)Ag compounds, demonstrating that DPPH can be added to the list of polarising agents for DNP-NMR spectroscopy. Furthermore, the hydrophobic DPPH free radical can be easily filtered out from the dissolution liquid when water is used as the dissolution solvent.
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