title: Evidence of structure-selective fragmentations in the tandem mass spectra of protonated hydroxyalkylamino-1,4-naphthoquinones formed by electrospray ionisation.
abstract: The collision-induced dissociation of protonated hydroxyalkylamino-1,4-naphthoquinones depends strongly on the structure of the substituent [NHCH(2)(CH(2))(n)OH, n = 1-5; or NHCH(2)CH(CH(3))OH] on the quinone ring. Protonated naphthoquinones with an unbranched hydroxypropylamino side chain (n = 3) undergo facile and characteristic CH(2)O loss, whereas isomeric [M + H](+) ions with a branched hydroxypropylamino side chain do not. When n = 1, CH(2)O elimination occurs less readily, accompanied by CH(3)N loss, thus allowing this shorter side chain to be identified. Higher homologous species (n = 3-5) do not expel CH(2)O, but instead eliminate C(n + 1)H(2n)O, C(n + 1)H(2n + 2)O and (for n = 5) C(2n + 1)H(2n + 1)O.
authors.affiliation: Division of Chemical and Forensic Sciences, School of Life Sciences, University of Bradford, Bradford, West Yorkshire BD7 1DP, UK. r.d.bowen@Bradford.ac.uk
authors.forename: Richard D
authors.initials: RD
authors.lastname: Bowen
authors.forename: Tariq
authors.initials: T
authors.lastname: Mahmood
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Maitland
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Mercer
authors.forename: Richard T
authors.initials: RT
authors.lastname: Gallagher