Recent developments in data acquisition, treatment and analysis with ion mobility‐mass spectrometry for lipidomics

Abstract

Lipids are involved in many biological processes and their study is constantly increasing. To identify a lipid among thousand requires of reliable methods and techniques. Ion Mobility (IM) can be coupled with Mass Spectrometry (MS) to increase analytical selectivity in lipid analysis of lipids. IM-MS has experienced an enormous development in several aspects, including instrumentation, sensitivity, amount of information collected and lipid identification capabilities. This review summarizes the latest developments in IM-MS analyses for lipidomics and focuses on the current acquisition modes in IM-MS, the approaches for the pre-treatment of the acquired data and the subsequent data analysis. Methods and tools for the calculation of Collision Cross Section (CCS) values of analytes are also reviewed. CCS values are commonly studied to support the identification of lipids, providing a quasi-orthogonal property that increases the confidence level in the annotation of compounds and can be matched in CCS databases. The information contained in this review might be of help to new users of IM-MS to decide the adequate instrumentation and software to perform IM-MS experiments for lipid analyses, but also for other experienced researchers that can reconsider their routines and protocols.

Integrating the potential of ion mobility spectrometry-mass spectrometry in the separation and structural characterisation of lipid isomers

“…These IMS analysers are mostly used for untargeted analysis, as all of the ionised molecules in a sample can be analysed in the same run. However, their resolution and their capacity to separate lipid isomers is limited ( Moran-Garrido et al, 2022 ). To address this issue, and to circumvent hardware modifications, several software-based approaches have been developed to increase the resolving power in DTIMS.…”

“…In targeted MS/MS, the ions of interest are listed and fragmented after filtering. Conversely, in untargeted approaches, all ions are fragmented and no prior knowledge about the sample composition is needed ( Moran-Garrido et al, 2022 ). Depending on the IMS-MS instrumentation, different approximations are adopted.…”

“…Depending on the IMS-MS instrumentation, different approximations are adopted. While DTIMS and TWIMS are best suited for untargeted methodologies ( Moran-Garrido et al, 2022 ); TIMS, FAIMS, DMS and DMA are best suited for targeted applications ( Jeanne Dit Fouque and Fernandez-Lima, 2019 ; Winter et al, 2019 ; Delafield et al, 2022 ). Targeted methodologies are mainly used in the study of isomers.…”

“…Both approaches have their advantages and disadvantages. For example, if IMS is located before the CID fragmentation (the most typical approach), the user can filter the data by the mass and the mobility of the precursor product, obtaining cleaner fragmentation spectra ( Moran-Garrido et al, 2022 ). This combination also enables the elucidation of most sn -positional isomers, but also of some acyl chain isomers of DG and TG in DI-FAIMS ( Bowman et al, 2017 ) and sn -regioisomers of PC in DI-FAIMS ( Bowman et al, 2017 ) and LC-DTIMS ( Odenkirk et al, 2022 ).…”

“…For a more comprehensive analysis of the use of IMS in combination with MS/MS and the different working modes that have been developed thus far, such as data dependent (DDA) or data independent acquisition (DIA) approaches, the reader can refer to a recent review published on the topic ( Moran-Garrido et al, 2022 ).…”