Ion mobility spectrometry and the omics: Distinguishing isomers, molecular classes and contaminant ions in complex samples

Abstract

Ion mobility spectrometry (IMS) is a widely used analytical technique providing rapid gas phase separations. IMS alone is useful, but its coupling with mass spectrometry (IMS-MS) and various front-end separation techniques has greatly increased the molecular information achievable from different omic analyses. IMS-MS analyses are specifically gaining attention for improving metabolomic, lipidomic, glycomic, proteomic and exposomic analyses by increasing measurement sensitivity (e.g. S/N ratio), reducing the detection limit, and amplifying peak capacity. Numerous studies including national security-related analyses, disease screenings and environmental evaluations are illustrating that IMS-MS is able to extract information not possible with MS alone. Furthermore, IMS-MS has shown great utility in salvaging molecular information for low abundance molecules of interest when high concentration contaminant ions are present in the sample by reducing detector suppression. This review highlights how IMS-MS is currently being used in omic analyses to distinguish structurally similar molecules, isomers, molecular classes and contaminant ions.

Optimization of a liquid chromatography-ion mobility-high resolution mass spectrometry platform for untargeted lipidomics and application to HepaRG cell extracts

“…Furthermore, the separation of isomers and isobars, and consequently, the acquisition of well-resolved fragmentation spectra is a challenge especially for lipidomics applications [103,104]. In order to obtain a less time-consuming but comprehensive platform, ion mobility spectrometry (IMS, a separation technique based on the mobility of ions through a buffer gas under the influence of an electric field) has been successfully integrated into LC-MS-based lipidomics and metabolomics workflows [96,105]. One of the key advantages of the IMS technique is that it can separate ions in milliseconds based on their shape and size, which is highly convenient for linking LC separations (minutes) and time-of-flight (TOF)-MS detection (microseconds) for the separation of E/Z isomers, sn-positional isomers, and increasing annotation confidence with the addition of collision cross section values [104,105].…”

Moisture modulates soil reservoirs of active DNA and RNA viruses

“…Metaproteomics is, however, challenging to perform in soil and there have been few successful examples to date 8 – 10 . However, improving techniques and new methodologies in proteomics have recently made it possible to delve deeper into soil proteomes for the detection of less-abundant proteins 11 , 12 . Therefore, here we used a multi-omics approach, combining DNA and RNA sequencing with metaproteomics, leveraging the strength of each omics method, to better understand how soil viruses respond to environmental changes.…”

Ion mobility collision cross-section atlas for known and unknown metabolite annotation in untargeted metabolomics

“…Importantly, ion mobility can rapidly separate metabolite ions based on their differences in rotationally averaged surface area or collision cross-section (CCS) 16,17 . It enables to distinguish the isomeric metabolites that commonly exist in biological samples [18][19][20][21] . Unlike retention time (RT) and MS/MS spectra that are prone to be affected by many experimental factors, CCS is highly reproducible across instruments and labs, and it is much more feasible to be standardized 16,22 .…”