title: Electron ionisation and electrospray ionisation mass spectrometric study of a series of isomeric methyl-, dimethyl- and trimethylalloxazines.
abstract: Electron ionisation (EI) mass spectra and electrospray ionisation (ESI) mass spectra at different cone voltages of a series of isomeric methyl- and dimethylalloxazines are discussed, and compared with those of lumichrome, and 1- and 3-methyllumichrome. Examination of ESI mass spectra taken at a higher cone voltage and the use of isotope-labelled methanol allow us to discuss the fragmentation pathways of [M+H]+ and [M-H](-) ions. The fragmentation pathways of all of the compounds and the characteristic fragment ions formed in EI-MS are compared with published data. The influence of methyl and dimethyl substituents in the benzene ring on the fragmentation pathways leading to the loss of 43 and 45 Da upon both electron and electrospray ionisation is described.
authors.affiliation: Faculty of Chemistry, A. Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland. dprukala@amu.edu.pl
authors.forename: Dorota
authors.initials: D
authors.lastname: Prukała
authors.forename: Wiesław
authors.initials: W
authors.lastname: Prukała
authors.forename: Ryszard
authors.initials: R
authors.lastname: Koczorowski
authors.forename: Igor V
authors.initials: IV
authors.lastname: Khmelinskii
authors.forename: Ewa
authors.initials: E
authors.lastname: Sikorska
authors.forename: Marek
authors.initials: M
authors.lastname: Sikorski
mesh_terms: D004583:Electrons; D005415:Flavins / Q000032:analysis* / Q000737:chemistry*; D007477:Ions; D007536:Isomerism; D008745:Methylation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D005415:Flavins; D007477:Ions; C008173:isoalloxazine