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Tissue Imaging and Proteomics Laboratory Instruments

Bruker 9.4T solariX

Bruker SolariX_5

This is our workhorse instrument for MALDI-MS Imaging (Imaging Mass Spectrometry or Tissue Imaging) experiments (the photo is of our actual instrument). It can also be used for routine spotted MALDI experiments or for infusion ESI (electrospray ionization) experiments, such as for characterization of an intact protein to identify sites of post-translational modifications and determination of just what those modifications are.

The 9.4T solariX in TIPL is routinely used to image metabolites (primary metabolites, lipids, specialized/secondary metabolites) in tissues of multiple organism types, from plant stems, roots, fruits and leaves to microbial community mats and to animal tissues.

Although the FTICR cell has a very large mass range capacity, the solariX platform includes a quadrupole pre-filter, which in our case sets a mass cutoff of ~3500 m/z. Thus, the instrument is ideal for MALDI-imaging of metabolites, lipids and peptides, but not really suitable for imaging of intact proteins (due to the fact that MALDI generates singly- or occasionally doubly-charged ions).  For protein imaging, we use instead the Bruker ultrafleXtreme TOF/TOF in TIPL, which is ideally suited for that type of experiment (see page here).

Features of the 9.4T solariX that make it ideal for MALDI-MS imaging experiments:

  • FT-ICR technology providing unrivaled mass accuracy
    • Our MALDI-Imaging experiments typically are run with mass accuracy of better than 0.2 ppm error (usually it is around 0.1 or lower).
    • This enables us to unambiguously assign formulae for compounds of interest, increasing confidence in the results.
  • Ultimate mass resolving power
    • We typically run Imaging experiments at mass resolutions of 150,000 or 400,000 FWHM (full width at half maximum) due to time constraints and because for many routine analyses ultrahigh resolution isn’t always needed.
    • However, the instrument can be routinely run at mass resolutions >1.5 million, increasing confidence in compound identification and increasing signal to noise, thereby increasing sensitivity. For some experiments, such resolution is important.
  • MALDI source with Smartbeam II laser
    • This fast scanning laser enables MALDI-imaging experiments to be run at significant time savings (and cost) compared to other instruments.
    • We typically run experiments at a scan rate of 2 Hz. For lower resolution experiments, 4 Hz experiments are also performed.
    • The Smartbeam II laser also has a narrow beam, enabling raster spacing of 10 µm without oversampling. This provides for high spatial resolution in addition to the high mass resolution provided by the ICR cell.
  • Optimized ion optics for sensitivity and mass range coverage
    • The sensitivity of this instrument exceeds the other instruments we have available to us, and is ideal for tissue imaging experiments.