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NameMr. Xizheng Diao
Organization or InstitutionUniversity of Florida
TopicMass Spectrometry

Selective gas-phase Schiff base formation of phosphatidylserine lipids in imaging mass spectrometry using charge


Xizheng Diao, Boone M. Prentice

Author Institution(s)

Department of Chemistry, University of Florida, Gainesville, FL


There are many compounds of similar mass, at both nominal (isobaric) and exact (isomeric) m/z, found in biological specimens. In an imaging mass spectrometry (IMS) experiment, these interfering molecules can result in the spatial distribution of an image representing the confluence of several compounds with overlapping m/z values, resulting in inaccurate depictions of molecular distributions. In order to mitigate this chemical noise, we have employed gas-phase derivatization to selectively react with only one of the overlapping ion populations, thereby allowing for gas-phase separation.

These inversion ion/ion reactions are performed on a solariX FTICR MS. Briefly, phosphatidylserine anions generated via matrix-assisted laser desorption/ionization and N,N,N’,N’-tetramethyl-N,N’-bis(6-oxohexyl)hexane-1,6-diaminium (TMODA) dications generated via electrospray ionization are sequentially isolated using a quadrupole mass filter and injected into a hexapole reaction cell. Following a reaction period, the product ions are transferred to the ICR cell where they are subjected to sustained off-resonance collision induced dissociation and then mass analyzed.

Only PS lipids resulted in Schiff base formation using the TMODA reagent, as determined by signature loss of water and observation of [PS-H+TMODA-H2O]+.

This chemistry is demonstrated using PS18:0/16:0 (m/z 762.528) and PE16:0/22:6 (m/z 762.507) standards and used to distinguish isobaric phospholipids generated from mouse brain tissues.