Ion Mobility Spectrometry

Abstract

Ion mobility spectrometry (IMS) is a widely used analytical technique providing gas-phase separations based on analyte size, shape, and charge. The multidimensional analyses possible by coupling IMS with mass spectrometry (IMS-MS) or between liquid chromatography (LC) and MS separations (LC-IMS-MS) can greatly enhance lipidomic measurements by simultaneously providing multiple molecular descriptors for each ion observed. The addition of IMS also specifically enhances isomer separations, signal filtering, molecular annotations, and structural characterization capabilities without impacting the MS or LC-MS analysis times. IMS is also advantageous in providing experimentally derived collision cross section (CCS) values. As unique molecular ion descriptors, CCS values can increase identification confidence for comparison to previously reported experimental and in silico CCS values or for investigation of CCS-specific molecular trends. This chapter introduces the basic concepts of IMS including the common principles and unique aspects of several IMS techniques that differ in their applied electric fields and gas flows. The benefits and limitations of these commonly used IMS platforms as well as their recent advancements in IMS technology and computational tools are also explored. Finally, novel applications of IMS for lipidomic measurements are investigated including IMS-MS imaging, IMS-MS shotgun lipidomics, and multidimensional LC-IMS-MS/MS analyses.