Structural elucidation and relative quantification of sodium- and potassium-cationized phosphatidylcholine regioisomers directly from tissue using electron induced dissociation

Relative Quantification of Lipid Isomers in Imaging Mass Spectrometry Using Gas-Phase Charge Inversion Ion/Ion Reactions and Infrared Multiphoton Dissociation

“…Electron induced dissociation (EID) has been used to identify sn -position and double bond position of lipid synthetic standards and lipids generated from biological specimens. − Additionally, it is one of the few methods that can identify regioisomeric (cis/trans) geometry of the double bond . However, the use of EID in imaging mass spectrometry experiments is difficult due to low fragmentation efficiencies. , …”

“…26 However, the use of EID in imaging mass spectrometry experiments is difficult due to low fragmentation efficiencies. 27,28 Gas-phase ion/ion reactions alter the ion type prior to dissociation and enable complementary structural information for many analytes. 29,30 Ion/ion reactions have proven to be useful in studying proteins, 31−36 peptides, 37−46 oligonucleotides, 47,48 and lipids.…”

Separation of Isobaric Lipids in Imaging Mass Spectrometry Using Gas-Phase Charge Inversion Ion/Ion Reactions

“…Alternative MS/MS approaches have been described in recent years to aid in compound separation and identification in imaging mass spectrometry experiments, such as gas-phase ion/molecule (e.g., ozone induced dissociation), , ion/electron reactions (e.g., electron induced dissociation), , and ion/photon reactions (e.g., ultraviolet photodissociation) to separate and identify lipids. , Recently, our lab described the use of gas-phase charge inversion ion/ion reactions in imaging mass spectrometry experiments. , This workflow involves the sequential generation of singly charged analyte ions produced from a tissue surface by MALDI and multiply charged reagent ions of the opposite polarity produced by electrospray ionization (ESI). These two ion populations are then mutually stored in an electrodynamic ion trap.…”

“…7 The type of fragment ion observed during a tandem mass spectrometry experiment is a function of the ion type selected for MS/MS and the type of ion activation that is performed, suggesting that other iterations of MS/MS may help resolve isobaric and isomeric interferences. 30 Alternative MS/MS approaches have been described in recent years to aid in compound separation and identification in imaging mass spectrometry experiments, such as gas-phase ion/molecule (e.g., ozone induced dissociation), 31,32 ion/ electron reactions (e.g., electron induced dissociation), 33,34 and ion/photon reactions (e.g., ultraviolet photodissociation) 35 to separate and identify lipids. 21,36 Recently, our lab described the use of gas-phase charge inversion ion/ion reactions in imaging mass spectrometry experiments.…”

Development of an Efficient On-Tissue Epoxidation Reaction Mediated by Urea Hydrogen Peroxide for MALDI MS/MS Imaging of Lipid C═C Location Isomers

“…Conventional tandem MS with low-energy collision-induced dissociation (CID) fails to locate CC due to the higher collision energy required to break the CC bond. To address this issue, alternative ion activation methods have been developed, such as electron impact excitation of ions from organics (EIEIO), − ultraviolet photodissociation (UVPD), , ion/ion reactions, − and ozone-induced dissociation (OzID), , some of which are compatible with MALDI MSI platforms − but often involve sophisticated modification of commercial mass spectrometers. Another isomer identification approach is to introduce a derivatization reaction before entering the mass spectrometer, which can convert CC bonds into cleavable functional groups under MS/MS conditions.…”