Detailed Structural Analysis of Lipids Directly on Tissue Specimens Using a MALDI-SpiralTOF-Reflectron TOF Mass Spectrometer

Shuichi Shimma,Michisato Toyoda,Ayumi Kubo,Takaya Satoh,Akos Vertes

doi:10.1371/journal.pone.0037107

Shuichi Shimma, Michisato Toyoda + Show 3 more

Open Access

https://doi.org/10.1371/journal.pone.0037107

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Journal: PLoS ONE	Publication Date: May 18, 2012
Citations: 34	License type: CC BY 4.0

Affiliation: Osaka University, JEOL (Japan)

Abstract

Direct tissue analysis using a novel tandem time-of-flight (TOF-TOF) mass spectrometer is described. This system consists of a matrix-assisted laser desorption/ionization ion source, a spiral ion trajectory TOF mass spectrometer “SpiralTOF (STOF)”, a collision cell, and an offset parabolic reflectron (RTOF). The features of this system are high precursor ion selectivity due to a 17-m flight path length in STOF and elimination of post-source decay (PSD) ions. The acceleration energy is 20 keV, so that high-energy collision-induced dissociation (HE-CID) is possible. Elimination of PSD ions allows observation of the product ions inherent to the HE-CID process. By using this tandem TOF instrument, the product ion spectrum of lipids provided detailed structural information of fatty acid residues.

Highlights

In recent years, direct tissue analysis including tissue profiling and imaging mass spectrometry has been at the forefront of research in mass spectrometry.[1,2,3,4,5] A wide variety of instrument types including time-of-flight (TOF) mass spectrometers, [6] quadrupole mass filters, ion traps, [7] orbitraps, [8] and Fourier transform mass spectrometers [9,10] have been described in the literatures
[15] Since the ions generated by matrixassisted laser desorption/ionization (MALDI) often undergo post-source decay (PSD), [16,17] the fragment ions generated by PSD and high-energy Collision-induced dissociation (CID) (HE-CID) overlap in the product ion spectrum when conventional MALDI-TOF-TOF instruments are used
Both spectra show a large number of signal peaks, but because of the characteristics of STOF, each peak was clearly separated and the noise level was quite low. These results demonstrate that even in tissue analysis, the high mass resolution was sufficient to separate monoisotopic ions for the subsequent MS/MS experiment

Summary

Introduction

Direct tissue analysis including tissue profiling and imaging mass spectrometry has been at the forefront of research in mass spectrometry.[1,2,3,4,5] A wide variety of instrument types including time-of-flight (TOF) mass spectrometers, [6] quadrupole mass filters, ion traps, [7] orbitraps, [8] and Fourier transform mass spectrometers [9,10] have been described in the literatures. Product ion spectra of peptide standards and a synthetic polymer obtained using MALDI-STOF-RTOF have already been reported.

Results

Conclusion