Clément PRAUD, PhD student in CEISAM MIMM team, will defend his thesis untitled “Development and assessment of UF 2D NMR methods for the analysis of metabolic mixtures hyperpolarized by d-DNP and at thermal equilibrium” on December 14th 2023 at 10h in CEISAM’s conference room « Marie Curie ».
Abstract
Hyperpolarized 13C NMR at natural abundance, relying on dissolution dynamic nuclear polarization (d-DNP), provides rich, sensitive and repeatable 13C NMR fingerprints of complex mixtures. Nevertheless, the increase of the NMR sensitivity comes with challenges, such as peak overlap and the difficulty to assign hyperpolarized 13C signals. Ultrafast (UF) 2D NMR spectroscopy offers a unique way to record heteronuclear 2D correlation maps, in a single scan and in less than 100 ms, of d-DNP hyperpolarized samples. A UF long-range HETCOR pulse sequence has been developed and optimised to record 2D correlation peaks, that links quaternary carbons and protons through long-range scalar couplings, offering useful assignment and structural information. In the case of metabolite mixture analysis, we showed that it was possible to record good quality spectra of natural-abundance molecules, polarized by d-DNP. Limits of quantification of the method are reported in the range of 1-50 mM in the sample cup, prior to dissolution, as well as a method repeatability close to 10% and a very good linearity with R² ≥ 0.90. The detailed comparison of two dissolution solvents, D2O and MeOD is provided, and the perspectives of such technique for complex-mixture analysis are addressed. In parallel, the analytical performance of a UF COSY pulse sequence is studied on 3 different spectrometer systems of the CEISAM NMR platform and the limit of quantifications of the method are reported.
Keywords
NMR spectroscopy of liquid, pulse sequences, Dynamic Nuclear Polarization, mixture analysis, metabolites, method assessment.