Separation and classification of lipids using differential ion mobility spectrometry

Area of Science:

• Analytical Chemistry
• Biochemistry
• Spectrometry

Background:

• Two-dimensional separations, like ion mobility spectrometry (IMS)/mass spectrometry (MS), use trend lines for classifying compounds based on structural and chemical properties.
• Major biomolecular classes typically occupy distinct trend line domains in IMS/MS.
• Strong correlation between conventional IMS and MS separations limits finer distinctions within compound classes.

Purpose of the Study:

• To investigate the potential of differential ion mobility spectrometry (FAIMS) for chemical class separation of lipids.
• To determine if FAIMS, being less correlated with MS than conventional IMS, can improve lipid subclass and fine category distinctions.
• To assess the impact of helium-rich gas environments on separation resolution.

Main Methods:

• Utilizing differential ion mobility spectrometry (FAIMS) coupled with mass spectrometry (MS) for 2-D separation of lipids.
• Analyzing the resulting trend lines to observe chemical class separation.
• Experimenting with helium-rich gas mixtures (up to 70% He) to evaluate resolution improvements.
• Applying the method to various lipid subclasses, including phospholipids, glycerolipids, and sphingolipids.

Main Results:

• FAIMS demonstrated effective separation of lipid subclasses, forming distinct and often non-overlapping trend line domains.
• Lipid categories with different functional groups or degrees of unsaturation were frequently separated.
• Separation resolution was enhanced in helium-rich gas environments, with glycerolipid isomers distinguished at 70% He.
• FAIMS showed greater independence from MS compared to conventional IMS for lipid analysis.

Conclusions:

• FAIMS offers a powerful approach for classifying lipids based on distinct trend line domains.
• This method enables finer distinctions within lipid subclasses and categories, surpassing conventional IMS/MS.
• The improved resolution in helium-rich gases further enhances the analytical capabilities of FAIMS for lipidomics.
• FAIMS holds significant promise for applications in shotgun lipidomics and targeted analysis of bioactive lipids.