Perspective on Developments in Ion Mobility Spectrometry-Mass Spectrometry Combined with Ion Spectroscopy

Combined with mass spectrometry, ion spectroscopy can obtain a spectrum of the target ion by measuring its intensity change, which is induced by laser strength and wavelength. It integrates the high sensitivity of mass spectrometry and the structural specificity of spectroscopy, and thus proves to be very useful in structure characterization of complex biomolecules, such as proteins, peptides, glycans, oligonucleotides, etc. However, the electronic or vibrational spectra becomes too complex to be resolved when analyzing isomeric ions. Ion mobility spectrometry (IMS) allows ionized molecules to be separated on the basis of mobilities in the gas phase, and its coupling with electrospray and MALDI ion sources opens up possibilities for structural studies of a wide range of biomolecules in gasphase. Ion mobility spectrometry coupled with mass spectrometry has seen spectacular growth for the last two decades. The introduction of ion mobility to ion spectroscopy has been of growing attention in recent years. While IMS can be used as an isomer filter to reduce spectral congestion of ions, highly resolved ion spectra facilitates the identification of the isomer peaks separated by IMS. Taken together, spectra and collision cross section (CCS) measurements on the same system prove to be rather useful for structural analysis and provide clearer spectroscopic fingerprint to isomers. Therefore, this paper briefly summarized advances in ion spectroscopy research based on ion mobility-mass spectrometry technology, introduced representative researches, and prospected possible development in multi-dimensional structural mass spectrometry.