Applications of ion-mobility mass spectrometry for lipid analysis

Abstract

The high chemical complexity of the lipidome is one of the major challenges in lipidomics research. Ion-mobility spectrometry (IMS), a gas-phase electrophoretic technique, makes possible the separation of ions in the gas phase according to their charge, shape, and size. IMS can be combined with mass spectrometry (MS), adding three major benefits to traditional lipidomic approaches. First, IMS-MS allows the determination of the collision cross section (CCS), a physicochemical measure related to the conformational structure of lipid ions. The CCS is used to improve the confidence of lipid identification. Second, IMS-MS provides a new set of hybrid fragmentation experiments. These experiments, which combine collision-induced dissociation with ion-mobility separation, improve the specificity of MS/MS-based approaches. Third, IMS-MS improves the peak capacity and signal-to-noise ratio of traditional analytical approaches. In doing so, it allows the separation of complex lipid extracts from interfering isobaric species. Developing in parallel with advances in instrumentation, informatics solutions enable analysts to process and exploit IMS-MS data for qualitative and quantitative applications. Here we review the current approaches for lipidomics research based on IMS-MS, including liquid chromatography-MS and direct-MS analyses of "shotgun" lipidomics and MS imaging.

Lipidomics: Techniques, Applications, and Outcomes Related to Biomedical Sciences

“…Following the ionization of lipids, the ion mobility technique can be applied as an option for an additional dimension of ion manipulation and separation prior to MS analysis [34]. Next, either Full MS or MS/MS analysis (see Box 3 for MS/MS techniques) or both can be performed depending on whether a targeted or global analysis is desired.…”

“…One of the common features is that ESI- and MALDI-MS are both applicable to these approaches although LC-MALDI-MS is operated off-line and not as commonly used as LC-ESI-MS. Another common feature is that shotgun and LC-MS approaches are both compatible to ion mobility MS [34] which adds an additional dimension of separation. The third feature is that after data acquisition and processing for species identification and quantification, same bioinformatics tools can be applied to the data from both platforms [37, 40].…”

Exploring Valuable Lipids in Diatoms

“…For example, isobaric molecules, which have the same m/z values and retention times, have the separation issues (Kliman et al, 2011). To this end, ion mobility mass spectrometry becomes an emerging technique to characterize lipid isomers with added separation dimension on conformational structure (Kliman et al, 2011;Paglia et al, 2015).…”

Recent Advances and Future Challenges in Modified Mycotoxin Analysis: Why HRMS Has Become a Key Instrument in Food Contaminant Research

“…In addition, once the pesticide has been identified using its retention time, exact mass, and drift time, the resulting cleaned mass spectrum facilitates the identification process. In line with these findings, the cleaning effect due to ion mobility separation on MS/MS spectra was demonstrated [86]. Applying the DIA mode for the MS analysis of complex extracts could result in MS/MS spectra containing a mixture of product ions derived from co-eluting precursors, complicating interpretation of the spectra and the overall identification process (Figure 4).…”

“…In addition, since CCS measurements are undertaken in the gas phase, remotely from the ion source, their values are not affected by sample matrix and are consistent between instruments and across a range of experimental conditions [86,93]. Taking into account the analytical effort made in recent years for validating extraction and detection procedure depending on the sample matrix, the great advantage offered by the CCS measurement is evident.…”