title: Metastable ions arising from pseudomolecular [M-H]- ions produced by fast-atom bombardment negative-ion mass spectrometry of ecdysteroids.
abstract: Metastable ions arising from pseudomolecular [M-H]- ions produced by fast-atom bombardment negative-ion mass spectrometry of a range of free ecdysteroids, ecdysteroid conjugates and polar metabolites were investigated by means of linked scanning at constant B/E. Free ecdysteroids displayed daughter-ion spectra which allow 20-hydroxyecdysteroids and ecdysteroids lacking C-20 hydroxylation to be readily distinguished. The ejection of acetic acid from acetylated ecdysteroids was also readily detectable. Characteristic metastable-ion decomposition of ecdysteroid acids was not observed, presumably as a result of charge localization. High-mass daughter ions were also lacking in the case of phosphate conjugates.
authors.affiliation: Department of Biochemistry, University of Liverpool, UK.
authors.forename: R P
authors.initials: RP
authors.lastname: Evershed
authors.forename: M C
authors.initials: MC
authors.lastname: Prescott
authors.forename: M
authors.initials: M
authors.lastname: Kabbouh
authors.forename: H H
authors.initials: HH
authors.lastname: Rees
mesh_terms: D026461:Ecdysteroids; D007447:Invertebrate Hormones / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment / Q000379:methods
chemical_list: D026461:Ecdysteroids; D007447:Invertebrate Hormones