Research Article

Journal of The American Society for Mass Spectrometry

, Volume 23, Issue 11, pp 2031-2042

First online:

Electron Detachment Dissociation of Underivatized Chloride-Adducted Oligosaccharides

  • James R. KornackiAffiliated withDepartment of Chemistry, University of MichiganDepartment of Chemistry, Northwestern University
  • , Julie T. AdamsonAffiliated withDepartment of Chemistry, University of MichiganMillennium Pharmaceuticals
  • , Kristina HåkanssonAffiliated withDepartment of Chemistry, University of Michigan Email author 


Chloride anion attachment has previously been shown to aid determination of saccharide anomeric configuration and generation of linkage information in negative ion post-source decay MALDI tandem mass spectrometry. Here, we employ electron detachment dissociation (EDD) and collision activated dissociation (CAD) for the structural characterization of underivatized oligosaccharides bearing a chloride ion adduct. Both neutral and sialylated oligosaccharides are examined, including maltoheptaose, an asialo biantennary glycan (NA2), disialylacto-N-tetraose (DSLNT), and two LS tetrasaccharides (LSTa and LSTb). Gas-phase chloride-adducted species are generated by negative ion mode electrospray ionization. EDD and CAD spectra of chloride-adducted oligosaccharides are compared to the corresponding spectra for doubly deprotonated species not containing a chloride anion to assess the role of chloride adduction in the stimulation of alternative fragmentation pathways and altered charge locations allowing detection of additional product ions. In all cases, EDD of singly chloridated and singly deprotonated species resulted in an increase in observed cross-ring cleavages, which are essential to providing saccharide linkage information. Glycosidic cleavages also increased in EDD of chloride-adducted oligosaccharides to reveal complementary structural information compared to traditional (non-chloride-assisted) EDD and CAD. Results indicate that chloride adduction is of interest in alternative anion activation methods such as EDD for oligosaccharide structural characterization.

Key words

MS/MS Tandem mass spectrometry CAD collision activated dissociation EDD electron detachment dissociation FT-ICR Fourier transform ion cyclotron resonance Carbohydrate Structural characterization Oligosaccharide Chloride adduct