Construction and testing of an atmospheric-pressure transmission-mode matrix assisted laser desorption ionisation mass spectrometry imaging ion source with plasma ionisation enhancement

Rory T Steven; Michael Shaw; Alex Dexter; Teresa Murta; Felicia M Green; Kenneth N Robinson; Ian S Gilmore; Zoltan Takats; Josephine Bunch

doi:10.1016/j.aca.2018.11.003

Construction and testing of an atmospheric-pressure transmission-mode matrix assisted laser desorption ionisation mass spectrometry imaging ion source with plasma ionisation enhancement

Anal Chim Acta. 2019 Mar 21:1051:110-119. doi: 10.1016/j.aca.2018.11.003. Epub 2018 Nov 14.

Authors

Rory T Steven¹, Michael Shaw², Alex Dexter³, Teresa Murta³, Felicia M Green³, Kenneth N Robinson³, Ian S Gilmore³, Zoltan Takats⁴, Josephine Bunch⁵

Affiliations

¹ National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI), Analytical Science Division, National Physical Laboratory (NPL), Teddington, TW11 0LW, UK. Electronic address: [email protected].
² Biotechnology Group, Analytical Science Division, National Physical Laboratory, Teddington, TW11 0LW, UK; UCL Touch Lab, Department of Computer Science, University College London, Gower Street, London, WC1 6BT, UK.
³ National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI), Analytical Science Division, National Physical Laboratory (NPL), Teddington, TW11 0LW, UK.
⁴ Imperial Collage London, Faculty of Medicine, Department of Surgery & Cancer, London, SW7 2AZ, UK.
⁵ National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI), Analytical Science Division, National Physical Laboratory (NPL), Teddington, TW11 0LW, UK; Imperial Collage London, Faculty of Medicine, Department of Surgery & Cancer, London, SW7 2AZ, UK. Electronic address: [email protected].

PMID: 30661607
DOI: 10.1016/j.aca.2018.11.003

Abstract

Matrix assisted laser desorption ionisation mass spectrometry (MALDI-MS) at atmospheric pressure (AP) is, with a few notable exceptions, overshadowed by its vacuum based forms and AP transmission mode (TM) MALDI-MS lacks the up-take its potential benefits might suggest. The reasons for this are not fully understood and it is clear further development is required to realise the flexibility and power of this ionisation method and geometry. Here we report the build of a new AP-TM-MALDI-MSI ion source with plasma ionisation enhancement. This novel ion source is used to analyse a selection of increasingly complex systems from molecular standards to murine brain tissue sections. Significant enhancement of detected ion intensity is observed in both positive and negative ion mode in all systems, with up to 2000 fold increases observed for a range of tissue endogenous species. The substantial improvements conferred by the plasma enhancement are then employed to demonstrate the acquisition of proof of concept tissue images, with high quality spectra obtained down to 10 × 10 μm pixel size.

Keywords: Atmospheric pressure MALDI MS; Mass spectrometry imaging; Matrix assisted laser desorption ionisation mass spectrometry; Plasma assisted ionisation; Transmission mode MALDI MS.

MeSH terms

Animals
Atmospheric Pressure*
Brain Chemistry
Equipment Design
Mice
Plasma Gases / chemistry*
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / instrumentation
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*

Substances

Plasma Gases