Structural characterization of hexoses and pentoses using lead cationization. An electrospray ionization and tandem mass spectrometric study
Résumé
The analytical potential of the complexation of isomeric underivatized hexoses (D-glucose, D-galactose, D-mannose, D-talose, D-fructose), methyl-glycosides (1-O-methyl--D-glucose and 1-O-methyl--D-glucose) and pentoses (D-ribose, D-xylose, D-arabinose and D-lyxose) by Pb 2+ ions, has been investigated by electrospray ionization and tandem mass spectrometry. Lead(II) ions react mainly with monosaccharides by proton abstraction to generate [Pb(monosaccharide)m-H] + ions (m=1-3). At low cone voltage, a less intense series of doubly charged ions of general formula [Pb(monosaccharide)n] 2+ is also observed. The maximum number n of monosaccharides surrounding a single Pb 2+ ion depends on the metal/monosaccharide ratio. Our study shows that MS/MS experiments have to be performed to differentiate Pb 2+-coordinated monosaccharides. Upon collision, [Pb(monosaccharide)-H] + species mainly dissociate according to cross-ring cleavages, leading to the elimination of CnH2nOn neutrals. The various fragmentation processes observed allow the C(1), C(2) and C(4) stereocenters of aldohexoses to be characterized, as well as a clear-cut aldoses/fructose distinction. Furthermore, careful analysis of MS/MS spectra also leads to successful aldopentose distinction. Lead cationization combined with tandem mass spectrometry therefore appears particularly useful to identify underivatized monosaccharides.
Origine : Fichiers produits par l'(les) auteur(s)
Loading...