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Urbańczyk, Mateusz; Shchukina, Alexandra; Gołowicz, Dariusz; Kazimierczuk, Krzysztof
doi: 10.1002/mrc.4796pmid: 30255516
NMR spectroscopy, used routinely for structure elucidation, has also become a widely applied tool for process and reaction monitoring. However, the most informative of NMR methods—correlation experiments—are often useless in this kind of applications. The traditional sampling of a multidimensional FID is usually time‐consuming, and thus, the reaction‐monitoring toolbox was practically limited to 1D experiments (with rare exceptions, e.g., single‐scan or fast‐sampling experiments). Recently, the technique of time‐resolved non‐uniform sampling (TR‐NUS) has been proposed, which allows to use standard multidimensional pulse sequences preserving the temporal resolution close to that achievable in 1D experiments. However, the method existed only as a prototype and did not allow on‐the‐fly processing during the reaction.
doi: 10.1002/mrc.4776pmid: 29927497
The development of new tools to improve the quality of nuclear magnetic resonance (NMR) spectra is a challenging task. The concept of “perfect NMR” includes the design of robust pulse sequences that allow an investigator to obtain undistorted pure in‐phase signals, with pure absorption lineshapes that are free of phase anomalies derived from undesired J modulations. Here, alternative NMR building blocks to the spin‐echo that are based on a general double SE module, known as a perfect‐echo, are reviewed. Several implementations to minimize/remove unwanted dispersive contributions in homonuclear and heteronuclear NMR experiments are described and illustrated with some examples of broad interest for small molecules.
Dubey, Durgesh; Chaurasia, Smriti; Guleria, Anupam; Kumar, Sandeep; Modi, Dinesh Raj; Misra, Ramnath; Kumar, Dinesh
doi: 10.1002/mrc.4763pmid: 29907975
Currently, there are no reliable biomarkers available that can aid early differential diagnosis of reactive arthritis (ReA) from other inflammatory joint diseases. Metabolic profiling of synovial fluid (SF)—obtained from joints affected in ReA—holds great promise in this regard and will further aid monitoring treatment and improving our understanding about disease mechanism. As a first step in this direction, we report here the metabolite specific assignment of 1H and 13C resonances detected in the NMR spectra of SF samples extracted from human patients with established ReA. The metabolite characterization has been carried out on both normal and ultrafiltered (deproteinized) SF samples of eight ReA patients (n = 8) using high‐resolution (800 MHz) 1H and 1H─13C NMR spectroscopy methods such as one‐dimensional 1H CPMG and two‐dimensional J‐resolved1H NMR and homonuclear 1H─1H TOCSY and heteronuclear1H─13C HSQC correlation spectra. Compared with normal SF samples, several distinctive 1H NMR signals were identified and assigned to metabolites in the 1H NMR spectra of ultrafiltered SF samples. Overall, we assigned 53 metabolites in normal filtered SF and 64 metabolites in filtered pooled SF sample compared with nonfiltered SF samples for which only 48 metabolites (including lipid/membrane metabolites as well) have been identified. The established NMR characterization of SF metabolites will serve to guide future metabolomics studies aiming to identify/evaluate the SF‐based metabolic biomarkers of diagnostic/prognostic potential or seeking biochemical insights into disease mechanisms in a clinical perspective.
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