title: High-energy collision-induced dissociation tandem mass spectrometry of regioisomeric lactose palmitic acid monoesters using matrix-assisted laser desorption/ionization.
abstract: BACKGROUND
  Structural characterization and differentiation of three newly synthesized lactose monopalmitate regioisomers at positions O-3, O-3' and O-6' were realized by single-stage matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF-MS) in the positive ion mode and by high-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS).
  
  
  METHODS
  A MALDI-TOF/TOF analyzer was utilized for the analysis of these isobaric lactose monopalmitate regioisomers. The CID-MS/MS spectra were acquired using high-energy cid with a 2 kV potential difference between the source acceleration voltage and the collision cell.
  
  
  RESULTS
  High-energy (CID) tandem mass spectrometry (MS/MS) analyses of the sodiated molecules, [M + Na](+), showed distinguishing cross-ring product ions and characteristic fingerprint product ions, which allowed the straight-forward mass spectrometric characterization of these different regiosiomers.
  
  
  CONCLUSIONS
  This investigation allowed us to unravel the novel fragmentation behavior of the sodiated regioisoimer molecules obtained from the mono-substituted D-lactose fatty acid esters using high-energy CID-TOF/TOF-MS/MS analyses. The high-energy CID of the [M + Na](+) ions from the isobaric lactose monopalmitate regioiosmers promoted the formation of characteristic (0,2) A2 cross-ring cleavage product ions.
authors: Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, A1B 3V6, Canada; Department of Chemistry, Faculty of Science, Damanhour University, Damanhour, Egypt.
authors: Mina R
authors: MR
authors: Narouz
authors: Sameh E
authors: SE
authors: Soliman
authors: Travis D
authors: TD
authors: Fridgen
authors: Mina A
authors: MA
authors: Nashed
authors: Joseph H
authors: JH
authors: Banoub
mesh_terms: D007785:Lactose / Q000737:chemistry*; D019308:Palmitic Acid / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D019308:Palmitic Acid; D007785:Lactose