Apr 10, 2023

Public workspaceHigh Spatial Resolution MALDI Imaging Mass Spectrometry Data Acquisition

DOI
https://dx.doi.org/10.17504/protocols.io.n92ldpq99l5b/v1
High Spatial Resolution MALDI Imaging Mass Spectrometry Data Acquisition
  • Katerina Djambazova1,
  • Angela Kruse1,
  • Jamie Allen1,
  • allison.b.esselman 1,
  • Madeline E. Colley1,
  • David Anderson1,
  • ali.zahraei 1,
  • Olof Isberg1,
  • Melissa Farrow1,
  • Jeff Spraggins1,
  • Martin Dufrense1
  • 1Vanderbilt University
  • VU Biomolecular Multimodal Imaging Center / Spraggins Research Group
    Tech. support email: [email protected]
Katerina V Djambazova
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DOI: https://dx.doi.org/10.17504/protocols.io.n92ldpq99l5b/v1
Protocol Citation: Katerina Djambazova, Angela Kruse, Jamie Allen, allison.b.esselman , Madeline E. Colley, David Anderson, ali.zahraei , Olof Isberg, Melissa Farrow, Jeff Spraggins, Martin Dufrense 2023. High Spatial Resolution MALDI Imaging Mass Spectrometry Data Acquisition. protocols.io https://dx.doi.org/10.17504/protocols.io.n92ldpq99l5b/v1
License: This is an open access protocol distributed under the terms of the Creative Commons Attribution License,  which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Protocol status: Working
We use this protocol and it's working
Created: February 08, 2023
Last Modified: October 18, 2023
Protocol Integer ID: 76683
Keywords: MALDI IMS, Lipid Imaging, maldi imaging mass spectrometry experiment, imaging mass spectrometry, mass spectrometry, negative ionization mode data acquisition in qtof mode, negative ionization mode data acquisition, spatial resolution imaging, bruker timstof flex instrument, imaging, instrument parameter, qtof mode
Abstract
This protocol provides the workflow and instrument parameters for setting up a MALDI imaging mass spectrometry experiment on a Bruker timsTOF Flex instrument. This protocol is intended for 10µm spatial resolution imaging of lipids (m/z 400 - 2000) in positive and negative ionization mode data acquisition in qTOF mode of operation.
Materials
Agilent ESI-L Tune Mix (Agilent Technologies, Santa Clara, CA)
Troubleshooting
Place slides in a MTP 2-slide holder. Scan slides using flatbed scanner, allowing for sufficient contrast to visualize the tissue boundary. Ensure the slides have fiducials.
Note
Fiducials are markings on the slide that can be used as reference points for teaching the slides (Step 4).

Load the 2-slide holder in the instrument. Open timsControl software and select appropriate MALDI IMS data acquisition method. Generate target profile by ensuring "Use Target Profile" is enabled. Check the height at a few different locations on the slide and ensure the difference is <10 µm.

Note
Example Positive/Negative Ionization Mode Parameters for 10µm MALDI IMS:
m/z 400 - 2000
Laser Power: 35 - 45%, Frequency: 10 000 Hz
Shots: 100 - 150 per pixel
Spot size: 10 µm with Beam scanning function disabled
Source temperature: ~50 oC


Calibrate the TOF with an external calibration using red phosphorus. Proceed if all calibration points are <1ppm standard deviation error and the calibration score is >99%.
Note
Red phosphorus is commonly used to perform calibration, however Agilent ESI-L Tune Mix can also be used for electrospray ionization.

List of Red Phosphorus Mass Calibration Peaks
AB
Positive mode Negative mode
278.7633 278.7644
402.6583 402.6594
464.6058 464.6069
526.5534 526.5545
650.4484 650.4495
774.3435 774.3445
898.2385 898.2396
960.1860 960.1870
1022.1335 1022.1346
1146.0286 1146.0297
1393.8187 1393.8198
1517.7137 1517.7148
1641.6088 1641.6099
1765.5038 1765.5049
1889.3989 1889.4000


Use the FlexImaging software to load the optical image of the slides. Teach the target position with three teaching points. Check the accuracy of the teaching by moving the stage to a fourth location.
Select desired tissue measurement region. Start data acquisition in the FlexImaging software.