Hyphenated HPLC-NMR is an extremely efficient analytical tool, which makes it possible to perform on-flow experiments where 1D NMR spectra are obtained in real time as the analytes are separated and eluted from the chromatographic column. However, it is incompatible with multidimensional NMR methods that form an indispensible tool for the study of complex mixtures. Recently, Frydman and co-workers have proposed an ultrafast 2D NMR approach, where a complete 2D NMR correlation can be recorded in a single scan, thus providing a solution to the irreversibility of hyphenated techniques. This paper presents the first implementation of on-line ultrafast HPLC-NMR. Ultrafast COSY spectra are acquired every 12 s in the course of a chromatographic run performed on a mixture of natural aromatic compounds. The results, obtained on a commercial HPLC-NMR setup, highlight the generality of the ultrafast HPLC-NMR methodology, thus opening the way to a number of applications in the numerous fields in which HPLC-NMR forms a routine analytical tool.
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http://dx.doi.org/10.1039/c2an16208c | DOI Listing |
Chem Sci
December 2024
State Key Laboratory of Catalysis, Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Zhongshan Road 457 Dalian 116023 China
In solid-state NMR, dipolar-based heteronuclear polarization transfer has been extensively used for sensitivity enhancement and multidimensional correlations, but its efficiency often suffers from undesired spin interactions and hardware limitations. Herein, we propose a novel dipolar-echo edited R-symmetry (DEER) sequence, which is further incorporated into the INEPT-type scheme, dubbed DEER-INEPT, for achieving highly efficient heteronuclear polarization transfer. Numerical simulations and NMR experiments demonstrate that DEER-INEPT offers significantly improved robustness, enabling efficient polarization transfer under a wide range of MAS conditions, from slow to ultrafast rates, outperforming existing methods.
View Article and Find Full Text PDFAnal Chim Acta
January 2025
State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, 361005, China. Electronic address:
Background: Nuclear Magnetic Resonance (NMR) is extensively utilized in research as a non-invasive technique for investigating molecular structures and composite components. The spatiotemporal encoding (SPEN) technique effectively accelerates multi-dimensional NMR experiments. In ultrafast SPEN NMR, the acquired data are divided into odd and even segments corresponding to the positive and negative gradients during the decoding stage, respectively.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Department of Chemistry-Ångström Laboratory, Uppsala University Box 523, 751 20, Uppsala, Sweden.
In this study, we present the synthesis and analysis of a novel, air-stable, and solvent-resistant phosphaalkene switch. Using this symmetric switch, we have demonstrated degenerate photoisomerization experimentally for the first time. With a combination of photochemical-exchange NMR spectroscopy, ultrafast transient absorption spectroscopy, and quantum chemical calculations, we elucidate the isomerization mechanism of this symmetric phosphaalkene, comparing it to two other known molecules belonging to this class.
View Article and Find Full Text PDFRadiologia (Engl Ed)
October 2024
Sección de Radiología Abdominal, Servicio de Radiodiagnóstico, Hospital Universitario Central de Asturias (HUCA), Oviedo, Asturias, Spain.
Magnetic resonance enterography is primarily indicated for inflammatory bowel diseases. The study of the gastrointestinal tract using MRI has become feasible due to the emergence of ultrafast sequences with higher spatial resolution and phased-array coils enabling wider fields of view. However, to ensure the quality of the examination, it is essential to have prior preparation with oral or rectal contrast to distend the lumen and improve the definition of the intestinal wall.
View Article and Find Full Text PDFRofo
October 2024
Pediatric Radiology, University Hospital Leipzig, Leipzig, Germany.
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