Spojeni vysokoucinne kapalinove chromatografie a hmotnostni spektrometrie

Coupled high-performance liquid chromatography and mass spectrometry with electrospray ionization and atmospheric pressure chemical ionization is used for the analysis of selected classes of compounds, for which this technique brings considerable advantages in comparison with other analytical techniquesSummary in EnglishAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Spojeni vysokoucinne kapalinove chromatografie a hmotnostni spektrometrie

Coupled high-performance liquid chromatography and mass spectrometry with electrospray ionization and atmospheric pressure chemical ionization is used for the analysis of selected classes of compounds, for which this technique brings considerable advantages in comparison with other analytical techniquesSummary in EnglishAvailable from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

New Chiral Synthons of 13C- or 15N-labelled α-amino acids

Easily available chiral synthons of α-amino acids selectively labelled with 13C or 15N could significantly simplify preparation of enantiomerically pure selectively isotopically substituted α-amino acids for NMR and MS studies of biological systems. Based on previously described preparation of labelled synthons of nucleophilic and electrophilic glycine, different approaches to labelled quaternary α-amino acids were evaluated. In the case of α-(13C)methyl α-amino acids, two alternatives exists:1. preparation of an alanine synthon by introduction of the α-(13C)methyl group into a glycine synthon followed by anattachment of a side chain;2. usage of α-amino acids synthons carrying a side chain and introduction of the α-(13C)methyl group.The second approach was found to be better suited for the preparative applications. An optimisation was done in orderto increase yields and decrease release of by-products to waste water

Syntheses, X-ray, MSn, NMR and CD structure determination of nickel(II) complexes of Schiff bases of (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide and aromatic alpha-amino acids

A preparative procedure for the synthesis of an important chiral synthon of side-chain protected tyrosine was developed and optimised for the minimisation of nickel salts waste. While preparing a similar side-chain protected tryptophan synthon, an unexpected low stability was found of the Boc-protective group of the tryptophan aromatic nitrogen during purification on silica gel. X-ray crystal structure determination, tandem mass spectrometry (MS/MS) and NMR were applied for the elucidation of the structures Of the prepared complexes and by-products. Stereochemistry of products of alpha-methylation of the complexes was assessed using a model tyrosine-derived compound. (C) 2008 Elsevier Ltd. All rights reserved

Development of metallocomplex amino acids synthons for the asymmetric preparation of α-amino acids by stereoselective introduction of a side chain. Evaluation of the model asymmetric preparation of alanine and β-13C monolabelled α-aminoisobutyric acid

In this communication the evaluation of eleven new metallocomplex alanine synthons bearing C2-symmetric benzyl groups with electron-donating and electron-withdrawing substituents is described. α-Methylated glycine synthons (alanine complexes) were evaluated alongside alanine synthons in order to obtain a deeper understanding of the relationship between their structures and stereochemistry of monoalkylated products and to choose several candidates for their further tests for stereospecific preparation of 6-[18F]FDOPA. Glycine-derived analogues of the complexes 3–5 are the best candidates for the development of a 6-[18F]FDOPA preparation procedure. In the model epimerisation reaction they demonstrated the best performance, much better compared to the previously described compound 2. Complexes 3, 5 and 8 are the best in asymmetric preparation of β-13C monolabelled α-aminoisobutyric acid. They have to be tested in the preparation of α-methyl amino acids like 6-[18F]-α-methylDOPA and 2-[18F]-α-methyltyrosine

Update on guidelines for lipidomics analysis and reporting

Ekroos K, Ejsing C, Liebisch G, et al. Update on guidelines for lipidomics analysis and reporting. Journal of the American Oil Chemists' Society. 2022;99(Suppl. 1):13-14

Recommendations for Good Practice in Mass Spectrometry-Based Lipidomics

Kofeler HC, Ahrends R, Baker ES, et al. Recommendations for Good Practice in Mass Spectrometry-Based Lipidomics. Journal of Lipid Research. 2021;62: 100138.In the last two decades, lipidomics has become one of the fastest expanding scientific disciplines in biomedical research. With an increasing number of new research groups to the field, it is even more important to design guidelines for assuring high standards of data quality. The Lipidomics Standards Initiative (LSI) is a community-based endeavor for the coordination of development of these best practice guidelines in lipidomics, and is embedded within the International Lipidomics Society (ILS). It is the intention of this review to highlight the most quality-relevant aspects of the lipidomics workflow, including preanalytics, sample preparation, mass spectrometry, and lipid species identification and quantitation. Furthermore, this review does not just highlight examples of best practice, but also sheds light on strengths, drawbacks, and pitfalls in the lipidomic analysis workflow. While this review is not designed to be a step-by-step protocol by itself, nor to be dedicated to a specific application of lipidomics, it should nevertheless provide the interested reader with links and original publications to obtain a comprehensive overview concerning the state of the art practices in the field. Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved