- Nitrogen-containing cyclic compounds as iminium ion sources for selected reaction monitoring detection of derivatized analytes
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Liquid chromatography–tandem mass spectrometry is one of the most sensitive tools for determination of trace amounts of analytes in metabolomics and proteomics. The highest sensitivity is achieved in selected reaction monitoring detection, which involves fragmentation of the molecular ion between two levels of mass selection. However, fragmentation of some compounds is complicated. Detection sensitivity of such analytes may be increased by derivatizing them with a specific moiety fragmentation of which results in product ion of high abundance. In this work, we reveal the influence of iminium ions' structures on their stability by comparing six nitrogen-containing cyclic compounds as derivatization reagents for tandem mass spectrometric analysis of amino group-containing analyte. Commercially available starting materials (piperidine, 2,6-dimethylpiperidine, 1-methylpiperazine, morpholine, pyrrolidine and 1-cyanomethyl-3-methylimidazolium ionic liquid) were used for the synthesis of corresponding carboxylic acids which were further used for derivatization of the model analyte tryptamine. Liquid chromatographic–mass spectrometric analysis of differently derivatized tryptamine was performed for the evaluation of release and stability of corresponding iminium ions under collision-induced dissociation conditions. As a result, morpholine moiety was shown being the most promising iminium ion source among tested compounds. Possible sub-fragmentation pathways of investigated iminium ions were discussed, and the structures of secondary product ions were proposed.
- ?ilionis, Andrius
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supporting information
p. 25 - 35
(2019/09/03)
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- N-alkylated carboxylic acid derivatives as anti-convulsant agents
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Described are compounds of the formula STR1 wherein R is hydrogen or loweralkyl; R1 is --OR2 or --NR2 R3 wherein R2 and R3 independently of one another denote hydrogen or loweralkyl; n is 0 or 1; R4 and R5 independently of one another denote loweralkyl or together form a 5 or 6 membered cycloalkyl substituted by hydrogen or loweralkyl, and together with the nitrogen atom, form a ring; and pharmaceutically acceptable salts thereof and their use as anticonvulsant agents in a method of controlling convulsions or seizures.
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- Diphenylboron Chelates of α-(Dialkylamino)carboxylic Acids and their N-Oxides
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α-(Dialkylamino)carboxylic acids and their N-oxides react with oxybis(diphenylborane) or similar diphenylborane derivatives to give five- or six-membered diphenylboron chelate rings, respectively, the structure of which is supported by spectroscopic evidence.
- Kliegel, Wolfgang,Graumann, Juergen
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p. 950 - 961
(2007/10/02)
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