Determination of Optimal Electrospray Parameters for Lipidomics in Infrared-Matrix-Assisted Laser Desorption Electrospray Ionization Mass Spectrometry Imaging

2020 ◽  
Vol 31 (2) ◽  
pp. 319-325
Author(s):  
M. Caleb Bagley ◽  
Måns Ekelöf ◽  
David C. Muddiman
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Electrospray Ionization Mass Spectrometry ◽  
Mass Spectrometry Imaging ◽  
Desorption Electrospray Ionization ◽  
Laser Desorption ◽  
Ionization Mass ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

scholarly journals Enhancing Metabolomic Coverage in Positive Ionization Mode Using Dicationic Reagents by Infrared Matrix-Assisted Laser Desorption Electrospray Ionization

Metabolites ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 810
Author(s):  
Ying Xi ◽  
David C. Muddiman
Keyword(s):  
Mass Spectrometry ◽  
Electrospray Ionization ◽  
Rat Liver ◽  
Mass Spectrometry Imaging ◽  
Desorption Electrospray Ionization ◽  
Laser Desorption ◽  
Ionization Mass ◽  
Ionization Mode ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

Mass spectrometry imaging is a powerful tool to analyze a large number of metabolites with their spatial coordinates collected throughout the sample. However, the significant differences in ionization efficiency pose a big challenge to metabolomic mass spectrometry imaging. To solve the challenge and obtain a complete data profile, researchers typically perform experiments in both positive and negative ionization modes, which is time-consuming. In this work, we evaluated the use of the dicationic reagent, 1,5-pentanediyl-bis(1-butylpyrrolidinium) difluoride (abbreviated to [C5(bpyr)2]F2) to detect a broad range of metabolites in the positive ionization mode by infrared matrix-assisted laser desorption electrospray ionization mass spectrometry imaging (IR-MALDESI MSI). [C5(bpyr)2]F2 at 10 µM was doped in 50% MeOH/H2O (v/v) electrospray solvent to form +1 charged adducted ions with anionic species (−1 charged) through post-electrospray ionization. This method was demonstrated with sectioned rat liver and hen ovary. A total of 73 deprotonated metabolites from rat liver tissue sections were successfully adducted with [C5(bpyr)2]2+ and putatively identified in the adducted positive ionization polarity, along with 164 positively charged metabolite ions commonly seen in positive ionization mode, which resulted in 44% increased molecular coverage. In addition, we were able to generate images of hen ovary sections showing their morphological features. Following-up tandem mass spectrometry (MS/MS) indicated that this dicationic reagent [C5(bpyr)2]2+ could form ionic bonds with the headgroup of glycerophospholipid ions. The addition of the dicationic reagent [C5(bpyr)2]2+ in the electrospray solvent provides a rapid and effective way to enhance the detection of metabolites in positive ionization mode.

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