Analysis of Tetrahydro-β-carbolines and Their Precursors by Electron Ionization Mass Spectrometry. Identification in Foodstuffs by Gas Chromatography/Mass Spectrometry

✍ Scribed by T. Herraiz

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 301 KB
• Volume: 11
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19970422)11:7<762::aid-rcm854>3.0.co;2-u

✦ Synopsis

Electron ionization (EI)-induced fragmentation was studied in 40 tetrahydro-β-carbolines, tryptamine and tryptophan derivatives. Tryptamine and tryptophan derivatives give the ion C 9 H 8 N + • (m/z 130) as the main fragment, accompanied by low-intensity molecular ions. Fragmentation in 1,2,3,4-tetrahydro-β-carbolines is dominated by the retro-Diels-Alder rearrangement that provides the ion C 10 H 9 N + • (m/z 143). The fragmentation of 1-methyl-1,2,3,4-tetrahydro-β-carbolines is dominated both by the loss of a methyl radical and by the retro-Diels-Alder fragmentation to give C 11 H 11 N + + (m/z 157). These compounds also exhibit an abundant molecular ion. 1-Ethyl-1,2,3,4-tetrahydro-β-carbolines lose the ethyl radical (M -CH 2 CH 3 ) and also show an abundant M + • . N-Methoxycarbonyl and N-trifluoroacetyl volatile derivatives of tetrahydro-β-carbolines and their precursors allow the separation and identification of these compounds by GC/MS. 1,3-Disubstituted 1,2,3,4-tetrahydro-β-carbolines give rise to two diastereoisomers (1S,3S) and (1R,3S) which are resolved by the GC/MS and provide similar mass spectra. The presence of 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid in foodstuffs (beer and orange juice) was demonstrated by GC/MS of its N-methoxycarbonyl methyl ester derivative. It is suggested that diet could be a source of tetrahydro-β-carbolines in mammals.