On Stereocontrol in Organocatalytic α-Chlorinations of Aldehydes

10.26434/chemrxiv.14229875 ◽

2021 ◽

Author(s):

Sebastian Ponath ◽

Chetan Joshi ◽

Amy T. Merrill ◽

Volker Schmidts ◽

Kim Greis ◽

...

Keyword(s):

Ion Mobility ◽

Resting State ◽

Comprehensive Analysis ◽

Ion Mobility Mass Spectrometry ◽

Concentration Profiles ◽

Nmr Studies ◽

Isotope Studies ◽

Configuration And Conformation

A comprehensive analysis of the organocatalytic α‐chlorination of aldehydes with N‐chloroimides and differ‐ ent catalysts is presented. For this reaction, alternate mechanisms were proposed that differ in the role of resting state intermediates and the rationalization of the observed enantioselectivity. This manuscript aims at resolving these funda‐ mental questions on the basis of rigorous structural characterization of intermediates (configuration and conformation), NMR studies, ion mobility‐mass spectrometry, concentration profiles, isotope studies, and DFT calculations. <br>

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Ion Mobility–Mass Spectrometry for Bioanalysis

Separations ◽

10.3390/separations8030033 ◽

2021 ◽

Vol 8 (3) ◽

pp. 33

Author(s):

Xavier Garcia ◽

Maria del Mar Sabaté ◽

Jorge Aubets ◽

Josep Maria Jansat ◽

Sonia Sentellas

Keyword(s):

Mass Spectrometry ◽

Liquid Chromatography ◽

Ion Mobility Spectrometry ◽

Ion Mobility ◽

Biological Samples ◽

Ion Mobility Mass Spectrometry ◽

Exogenous Compounds ◽

Analytical Separation

This paper aims to cover the main strategies based on ion mobility spectrometry (IMS) for the analysis of biological samples. The determination of endogenous and exogenous compounds in such samples is important for the understanding of the health status of individuals. For this reason, the development of new approaches that can be complementary to the ones already established (mainly based on liquid chromatography coupled to mass spectrometry) is welcomed. In this regard, ion mobility spectrometry has appeared in the analytical scenario as a powerful technique for the separation and characterization of compounds based on their mobility. IMS has been used in several areas taking advantage of its orthogonality with other analytical separation techniques, such as liquid chromatography, gas chromatography, capillary electrophoresis, or supercritical fluid chromatography. Bioanalysis is not one of the areas where IMS has been more extensively applied. However, over the last years, the interest in using this approach for the analysis of biological samples has clearly increased. This paper introduces the reader to the principles controlling the separation in IMS and reviews recent applications using this technique in the field of bioanalysis.

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Past and future trends of Egypt’s water consumption and its sources

Nature Communications ◽

10.1038/s41467-021-24747-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Catherine A. Nikiel ◽

Elfatih A. B. Eltahir

Keyword(s):

Economic Growth ◽

Virtual Water ◽

Comprehensive Analysis ◽

Future Trends ◽

Nile Water ◽

The Gift ◽

Per Capita ◽

The 1960S

AbstractFor millennia the Nile supplied Egypt with more water than needed. As the population grew and the economy expanded, demand on water increased accordingly. Here, we present a comprehensive analysis to reconstruct how total demand on water outstripped supply of the Nile water in the late 1970s, starting from a surplus of about 20 km3 per year in the 1960s leading to a deficit of about 40 km3 per year by the late 2010s. The gap is satisfied by import of virtual water. The role of economic growth in driving per capita demand on water is quantified based on detailed analysis of water use by agriculture and other sectors. We develop and test an empirical model of water demand in Egypt that relates demand on water to growth rates in the economy and population. Looking forward, we project that within this decade of the 2020 s, under nominal scenarios of population and economic growth, Egypt is likely to import more virtual water than the water supplied by the Nile, bringing into question the historical characterization of Egypt as “the gift of the Nile”.

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Recent advances in ion mobility–mass spectrometry for improved structural characterization of glycans and glycoconjugates

Current Opinion in Chemical Biology ◽

10.1016/j.cbpa.2017.10.007 ◽

2018 ◽

Vol 42 ◽

pp. 1-8 ◽

Cited By ~ 28

Author(s):

Zhengwei Chen ◽

Matthew S Glover ◽

Lingjun Li

Keyword(s):

Mass Spectrometry ◽

Structural Characterization ◽

Ion Mobility ◽

Ion Mobility Mass Spectrometry ◽

Recent Advances

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Structural Characterization of Methylenedianiline Regioisomers by Ion Mobility-Mass Spectrometry and Tandem Mass Spectrometry. 4. 3-Ring and 4-Ring Isomers

Analytical Chemistry ◽

10.1021/acs.analchem.8b04103 ◽

2018 ◽

Vol 90 (24) ◽

pp. 14453-14461 ◽

Cited By ~ 1

Author(s):

Tiffany M. Crescentini ◽

Sarah M. Stow ◽

Jay G. Forsythe ◽

Jody C. May ◽

John A. McLean ◽

...

Keyword(s):

Mass Spectrometry ◽

Tandem Mass Spectrometry ◽

Structural Characterization ◽

Ion Mobility ◽

Ion Mobility Mass Spectrometry ◽

Tandem Mass

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A Novel Approach to Characterize the Lipidome of Marine Archaeon Nitrosopumilus maritimus by Ion Mobility Mass Spectrometry

Frontiers in Microbiology ◽

10.3389/fmicb.2021.735878 ◽

2021 ◽

Vol 12 ◽

Author(s):

Kai P. Law ◽

Wei He ◽

Jianchang Tao ◽

Chuanlun Zhang

Keyword(s):

Mass Spectrometry ◽

Cross Sections ◽

Ion Mobility ◽

Resolving Power ◽

Ion Mobility Mass Spectrometry ◽

Ion Chemistry ◽

Lipid Species ◽

Mobility System ◽

Archaeal Lipids

Archaea are differentiated from the other two domains of life by their biomolecular characteristics. One such characteristic is the unique structure and composition of their lipids. Characterization of the whole set of lipids in a biological system (the lipidome) remains technologically challenging. This is because the lipidome is innately complex, and not all lipid species are extractable, separable, or ionizable by a single analytical method. Furthermore, lipids are structurally and chemically diverse. Many lipids are isobaric or isomeric and often indistinguishable by the measurement of mass or even their fragmentation spectra. Here we developed a novel analytical protocol based on liquid chromatography ion mobility mass spectrometry to enhance the coverage of the lipidome and characterize the conformations of archaeal lipids by their collision cross-sections (CCSs). The measurements of ion mobility revealed the gas-phase ion chemistry of representative archaeal lipids and provided further insights into their attributions to the adaptability of archaea to environmental stresses. A comprehensive characterization of the lipidome of mesophilic marine thaumarchaeon, Nitrosopumilus maritimus (strain SCM1) revealed potentially an unreported phosphate- and sulfate-containing lipid candidate by negative ionization analysis. It was the first time that experimentally derived CCS values of archaeal lipids were reported. Discrimination of crenarchaeol and its proposed stereoisomer was, however, not achieved with the resolving power of the SYNAPT G2 ion mobility system, and a high-resolution ion mobility system may be required for future work. Structural and spectral libraries of archaeal lipids were constructed in non-vendor-specific formats and are being made available to the community to promote research of Archaea by lipidomics.

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