Reaction of Ions from Pyrolyzed Levoglucosan with Adventitious Water in a Quadrupole Ion Trap (2015)
Undergraduates: Chelsea Tyler, Sandra E. Spencer Gary Glish
Faculty Advisor: Gary Glish
Department: Chemistry
The pyrolysis products of natural polymers often exhibit very similar and structurally uninformative neutral losses, such as the neutral loss of a water molecule, during collision induced dissociation (CID) in ion trap mass spectrometers. However, some ions undergo uncommon, and therefore characteristic, reactions. Protonated levoglucosan ions (m/z 163) react with adventitious water vapor in the ion trap to generate a product [M+H+18]+ (m/z 181). By trapping the protonated molecule of levoglucosan at m/z 163 for different times after isolation, the reaction kinetics for the production of m/z 181 from m/z 163 have been studied. Data has shown that the different solvent systems produce different reaction kinetics of protonated levoglucosan. When water is completely removed from the solvent, the extent of reaction does not change with time. However, when water is replaced by deuterium oxide, the same ions are produced with different reaction kinetics; suggesting production of different isometric structures dependent on the composition of the solvent. Such reactions allow levoglucosan to be uniquely identified in the presence of several other isomers/isobars formed during the pyrolysis process.