Benjamin LORANDEL, PhD student in CEISAM MIMM team, will defend his thesis untitled “Development of ultrafast diffusion NMR methods for the analysis of mixtures” on December 12th 2023 at 10h in CEISAM’s conference room « Marie Curie ».
Abstract
Diffusion-ordered NMR spectroscopy (DOSY) is a powerful tool for the analysis of mixtures. DOSY experiments rely on a pair of magnetic-field gradient pulses separated by a delay, that result in diffusion-weighting of the NMR signals. This method is well suited to the analysis of mixtures, because of its capacity to separate the signals as a function of the diffusion coefficients of the mixture’s components. Conventional DOSY experiments take several minutes or more, because a series of spectra are recorded, with incremented values of the gradient pulse amplitude. This is a limitation for the analysis of mixtures that evolve in time, either due to chemical reactions or because they are hyperpolarised. This work focuses on the spatially encoded (SPEN) DOSY experiment, that makes it possible to collect a complete DOSY data set in a single scan, by spatial parallelisation along the gradient dimension. In a first instance, the gradient field non-uniformity was measured and the retrieved gradient map was implemented in the processing of conventional and SPEN DOSY data. Then, the use of multivariate analysis methods was assessed towards a set of two-components’ mixtures, whose results were compared to the univariate processing ones. Finally, 13C SPEN DOSY experiments were launched on a hyperpolarised mixture of metabolites at natural abundance. The combination of such SPEN DOSY experiments to hyperpolarization techniques suggests encouraging perspectives towards the analysis of complex mixtures.
Keywords
Liquid-state NMR, DOSY, spatial encoding, mixtures, hyperpolarisation