Identifying Double Bond Positions in Phospholipids Using Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry Based on Oxygen Attachment Dissociation

Abstract

Lipids, a class of biomolecules, play a signi cant role in the physiological system. In this study, gas-phase hydroxyl radicals (OH•) and atomic oxygens (O) were introduced into the collision cell of a triple quadruple mass spectrometer (TQ-MS) to determine the positions of the double bond in unsaturated phospholipids. A microwave-driven compact plasma generator was used as the OH•/O source. e reaction between OH•/O and the precursor ions passing through the collision cell generates product ions that correspond to the double bond positions in the fatty acyl chain. is double bond position speci c fragmentation process initiated by the attachment of OH•/O to the double bond of a fatty acyl chain is a characteristic of oxygen attachment dissociation (OAD). A TQ-MS incorporating OAD, in combination with liquid chromatography, permitted a high throughput analysis of the double bond positions in complex biomolecules. It is important to know the precise position of double bonds in lipids, since these molecules can have widely different functionalities based on the position of the double bonds. e assignment of double bond positions in a mixture of eight standard samples of phosphatidylcholines (phospholipids with choline head groups) with multiple saturated fatty acyl chains attached was successfully demonstrated.

Computational mass spectrometry accelerates C = C position-resolved untargeted lipidomics using oxygen attachment dissociation

“…Lipid extraction for human plasma was performed according to a previous report 50 . Briefly, an aliquot of 40 µL of NIST SRM 1950 plasma sample was added to 200 µL of ice-cold CHCl 3 and vortexed for 10 s. After 1 h of incubation on ice, 400 µL of ice-cold MeOH containing 10 µL of EquiSPLASH, 20 µM palmitic acid-d3, and 20 µM stearic acid-d3 were added and vortexed for 10 s. After 2 h incubation on ice, the solvent tube was centrifuged at 2000 × g for 10 min at 4 °C, and 400 µL of supernatant was transferred to LC/MS vials (Agilent Technologies).…”

“…; and exclusion time of precursor ion, 0 s. Mass calibration was automatically performed using a calibration delivery system (CDS) with a sub-interface. The experimental setup for OAD-MS/MS is described in detail elsewhere 50 . Briefly, O/OH was generated via the microwave discharge of water vapor.…”

“…OAD-MS/MS method has also demonstrated its practicality for the annotation of C = C positions in a previous study 49 . OAD-MS/MS and OzID have a similar feature in which both fragmentations occur due to the electrophilicity of oxygen atoms; compared to an ozone generator, OAD-MS/MS can utilize water as a safe radical source 50 . Importantly, our approach integrates the LC-CID-MS/MS and LC-OAD-MS/MS data.…”

Computational mass spectrometry accelerates C=C position-resolved untargeted lipidomics using oxygen attachment dissociation

“…OAD-MS/MS method has also demonstrated its practicality for the annotation of C=C positions in a previous study 45 . OAD-MS/MS and OzID have a similar feature in which both fragmentations occur due to the electrophilicity of oxygen atoms; however, compared to an ozone generator, OAD-MS/MS can utilize water as a safe radical source 46 . Importantly, our approach integrates the LC-CID-MS/MS and LC-OAD-MS/MS data.…”