title: Diagnostic positive and negative ion fast atom bombardment mass spectrometry of low-molecular-weight ammonium compounds of marine origin.
abstract: Five ammonium compounds--betaine, taurine, homarine, trigonelline and tetramethylammonium chloride--were investigated by positive and negative ion fast atom bombardment (FAB) mass spectrometry. Observation of the parent cation [M + H]+ together with series of clusters (e.g. [nM + H]+, n = 2-5) and fragmentation patterns in the positive FAB mode may be used diagnostically as a fingerprint of the compound. The shifts in mass and relative intensity by addition of trichloroacetic acid and metal salts offer corroborating information of the identity of a compound in a mixture. The FAB negative ion spectra were characterized by clusters incorporating the anion (e.g. [M + Cl]-) but are generally less informative than the spectra obtained in the positive mode.
authors.affiliation: Department of General and Organic Chemistry, University of Copenhagen, Denmark.
authors.forename: C
authors.initials: C
authors.lastname: Larsen
authors.forename: U
authors.initials: U
authors.lastname: Anthoni
authors.forename: C
authors.initials: C
authors.lastname: Christophersen
authors.forename: P H
authors.initials: PH
authors.lastname: Nielsen
mesh_terms: D000470:Alkaloids / Q000032:analysis; D000818:Animals; D001622:Betaine / Q000032:analysis; D002013:Bryozoa / Q000032:analysis*; D013058:Mass Spectrometry / Q000379:methods*; D010848:Picolinic Acids / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D013654:Taurine / Q000032:analysis
chemical_list: D000470:Alkaloids; D010848:Picolinic Acids; D000644:Quaternary Ammonium Compounds; D013654:Taurine; C009560:trigonelline; D001622:Betaine; C027917:tetramethylammonium; C010981:homarine