Authors: Élida Alechaga Encarnación Moyano Maria Teresa Galceran
Publish Date: 2015/12/23
Volume: 408, Issue: 4, Pages: 1269-1277
Abstract
Nowadays most LCMS methods rely on tandem mass spectrometry not only for quantitation and confirmation of compounds by multiple reaction monitoring MRM but also for the identification of unknowns from their product ion spectra However gasphase reactions between charged and neutral species inside the mass analyzer can occur yielding product ions at m/z values higher than that of the precursor ion or at m/z values difficult to explain by logical losses which complicate mass spectral interpretation In this work the formation of adduct ions in the mass analyzer was studied using several mass spectrometers with different mass analyzers ion trap triple quadrupole and quadrupoleOrbitrap Heterocyclic amines AαC MeAαC TrpP1 and TrpP2 photoinitiators BP and THBP and pharmaceuticals phenacetin and levamisole were selected as model compounds and infused in LCQ Classic TSQ Quantum Ultra AM and QExactive Orbitrap ThermoFisher Scientific mass spectrometers using electrospray as ionization method The generation of ionmolecule adducts depended on the compound and also on the instrument employed Adducts with neutral organic solvents methanol and acetonitrile were only observed in the ion trap instrument LCQ Classic because of the ionization source onaxis configuration and the lack of gasphase barriers which allowed inertial entrance of the neutrals into the analyzer Adduct formation only with water in the triple quadrupole instruments was less abundant than in the ion trap and quadrupoleOrbitrap mass spectrometers because of the lower residence time of the reactive product ions in the mass analyzer The moisture level of the CID and/or damper gas had a great effect in beamlike mass analyzers such as triple quadrupole but not in traplike mass analyzers probably because of the long residence time that allowed adduct formation even with very low concentrations of water inside the mass spectrometerThe authors acknowledge financial support received from the Spanish Ministry of Economy and Competitiveness under the project CTQ201230836 and from the Agency for Administration of University and Research Grants Generalitat de Catalunya Spain under the project 2014 SGR539 The authors also acknowledge Dr Josep Caixach’s assistance with the Exactive mass spectrometer
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