Solvation in gas-phase reactions of sulfonic group containing ionic liquids in electrospray ionization quadrupole ion trap mass spectrometry.

In electrospray ionization (ESI) quadrupole ion trap mass spectrometry, certain fragment ions generated in the ion trap from a series of sulfonic group containing ionic liquids (ILs) are found to undergo ion-molecule reactions with ESI solvent molecules (water, acetonitrile and methanol) to form adduct species. These unexpected solvated fragment ions severely complicate the interpretation of mass spectrometric data. Multi-stage fragmentation mass spectra were used to ascertain the chemical structures of these adduct species. It is important that solvation must be taken into account in order to prevent erroneous data interpretation for sulfonic group containing ILs.