When exposed to a constant electric field, ions in the gas phase move at constant drift velocities; the proportionality constant between an ion’s velocity and the applied electric field is termed the ion mobility. Correspondingly, ion mobility spectrometry (IM) is a gas phase separation technique in which analyte ions (as small as atomic ions and up to charged aerosol particles) are separated temporally or spatially in an electric. Recent years have seen increased usage of IM in two specific applications. First, it is used as a pre-separation technique with mass spectrometry to better identify analytes in complex mixtures. Second, IM is used as a tool to characterize the structures of protein and multiprotein complex ions in the gas phase. In both of these applications, IM is used primarily as a structural characterization tool, and the chemical information obtained in measurement is limited to collision cross section inference (a parameter directly linked to ion mobility). This presentation will discuss novel applications of IM developed in our laboratory group, where measurements go beyond collision cross section determination. Specifically, in conjunction with mass spectrometry, we are developing techniques to examine ion-neutral complex formation in the gas phase (with applications in chemical warfare agent detection, fundamental studies of ion-induced nucleation, and measurement of the properties of atmospheric nanoclusters) and as a standalone technique we utilize IM to examine nanoparticle-protein conjugation. Also discussed will be the potential application of ion mobility-mass spectrometry in air pollution monitoring, using newly developed data inversion schemes to isolate atmospheric aerosol populations from one another.














Chris Hogan (University of Minnesota)