Abstract
Ion mobility-mass spectrometry (IM-MS) has proven to be a highly informative technique for the characterization of lipids from cells and tissues. We report the combination of hydrophilic-interaction liquid chromatography (HILIC) with traveling-wave IM-MS (TWIM-MS) for comprehensive lipidomics analysis. Main lipid categories such as glycerolipids, sphingolipids, and glycerophospholipids are separated on the basis of their lipid backbones in the IM dimension, whereas subclasses of each category are mostly separated on the basis of their headgroups in the HILIC dimension, demonstrating the orthogonality of HILIC and IM separations. Using our previously established lipid calibrants for collision cross-section (CCS) measurements in TWIM, we measured over 250 CCS values covering 12 lipid classes in positive and negative modes. The coverage of the HILIC-IM-MS method is demonstrated in the analysis of Neuro2a neuroblastoma cells exposed to benzalkonium chlorides (BACs) with C10 or C16 alkyl chains, which we have previously shown to affect gene expression related to cholesterol and lipid homeostasis. We found that BAC exposure resulted in significant changes to several lipid classes, including glycerides, sphingomyelins, phosphatidylcholines, and phosphatidylethanolamines. Our results indicate that BAC exposure modifies lipid homeostasis in a manner that is dependent upon the length of the BAC alkyl chain.
Highlights
Ion mobility-mass spectrometry (IM-MS) has proven to be a highly informative technique for the characterization of lipids from cells and tissues
We have recently demonstrated that the choice of calibrant has a significant impact on the collision cross-section (CCS) values generated for phospholipids on traveling wave ion mobility (TWIM)-MS platforms [36]
We demonstrated here that treatment of neuroblastoma cells with benzalkonium chloride (BAC)-C16 and BAC-C10 resulted in major revisions to lipid homeostasis affecting sterol, sphingolipid, glycerolipid, and phospholipid metabolism
Summary
Ion mobility-mass spectrometry (IM-MS) has proven to be a highly informative technique for the characterization of lipids from cells and tissues. We report the combination of hydrophilic-interaction liquid chromatography (HILIC) with traveling-wave IM-MS (TWIM-MS) for comprehensive lipidomics analysis. Shotgun lipidomics relies on partial intrasource separation of lipid classes through varying the pH of the lipid solution and identification of lipid species by their characteristic fragmentation in tandem MS analysis [9, 17]. This approach has the advantage of being high-throughput, but it has several disadvantages: a) suppression of low-abundant species by major polar lipids such as phosphatidylcholines; b) difficulty in analysis of lipid species that are poorly ionized by ESI; and c) inability to provide structural information on isobaric and isomeric species.
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