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High-energy collision-induced dissociation tandem mass spectrometry of regioisomeric lactose palmitic acid monoesters using matrix-assisted laser desorption/ionization

Authors

  • Mina R. Narouz,

    1. Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
    2. Department of Chemistry, Faculty of Science, Damanhour University, Damanhour, Egypt
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  • Sameh E. Soliman,

    1. Department of Chemistry, Faculty of Science, Alexandria University, Alexandria, Egypt
    2. NIDDK, LBC, National Institutes of Health, Bethesda, MD, USA
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  • Travis D. Fridgen,

    1. Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
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  • Mina A. Nashed,

    1. Department of Chemistry, Faculty of Science, Alexandria University, Alexandria, Egypt
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  • Joseph H. Banoub

    Corresponding author
    1. Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
    2. Fisheries and Oceans Canada, Science Branch, Environmental Sciences Division, St John's, Newfoundland, Canada
    • Correspondence to: J. H. Banoub, Fisheries and Oceans Canada, Science Branch, Special Projects, P.O. Box 5667, St John's, Newfoundland, A1C 5X1, Canada.

      E-mail: banoubjo@dfo-mpo.gc.ca

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Abstract

RATIONALE

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 0,2A2 cross-ring cleavage product ions. Copyright © 2013 John Wiley & Sons, Ltd.

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