Lipid analysis and lipidomics investigation by ambient mass spectrometry

Lipids are important components for biological organisms by acting as cell membrane matrices and signaling molecules, etc. Lipid analysis and lipidomics investigation play crucial roles in the exploration of lipid's biological functions for biosomes. Mass spectrometry (MS) is the first choice for lipid analysis and lipidomics investigation. The developments of ambient ionization methods give MS the opportunity for rapid, real-time, in situ, and in vivo analysis of complicated samples under ambient conditions, providing novel lipidomics approaches for in-depth investigation of the roles and mechanisms that lipids play for organisms. In this article, we review the published studies of lipid analysis and lipidomics investigation by ambient MS within the last 5 years (from 2015 to 2020). The analytical strategies to achieve lipidomics by various ambient ionization methods are classified for discussion, and their typical applications are commented. Moreover, the precise structural characterizations of lipid carbon-carbon double bond locations and stereospecific numbering positions are highlighted.