Liquid Chromatography - Mass Spectrometry of Zwitterionic Liquids

We have implemented full mass spectrometric assay of several 3-(1-alkyl-2-methylimidazolio)propanesulfonates, which are known as zwitterionic liquids (ZILs). Hydrophilic interaction liquid chromatography (HILIC) column and different mobile phases in both isocratic and gradient elution conditions were used for separation of the compounds present in these samples. The structures of the impurities have been confirmed by LC-MS/MS experiments. In addition, fragmentation pathways of ZILs were studied for different collision energies (0-50 eV) in positive electrospray ionization (ESI) mode under collision-induced dissociation conditions. Several new routes of fragmentation are briefly discussed. These include possible rearrangements and imidazolium ring expansions, which hypothetically proceed through carbocationic intermediates in the gas phase. Currently these processes are studied in a more detailed fashion.