Enhancing Mass Spectrometry Capabilities

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MALDI/ESI Injector

Instrumentation

Spectroglyph LLC offers a new product, MALDI/ESI Injector interface, concurrently enabling both elevated pressure (EP) MALDI and ESI capabilities.
The interface is compatible with Thermo's OrbitrapTM Q Exactive, Q Exactive Plus, Q Exactive HF and OrbitrapTM Elite, as illustrated in Figures 1-2.
Figure 1. MALDI/ESI Injector coupled to Thermo's OrbitrapTM Q Exactive
Figure 2: MALDI/ESI Injector coupled to Thermo's OrbitrapTM Elite

The MALDI/ESI Injector layout is shown in detail in Figure 3.

Stage movement is synchronized with Orbitrap spectrum acquisition using hardware triggers.
As a result, microscan numbers reported in a position file (XML format) are directly correlated to spectrum numbers in Thermo's RAW file.
The latter is processed by Xcalibur software (Thermo Fisher Scientific).
Hardware-level synchronization makes image reconstruction and alignment readily available.
Figure 3: MALDI/ESI Injector Layout

Imaging Capability

A dual translation stage used in MALDI/ESI Injector (Zaber, Vancouver, BC) handles standard hystology slides, whose dimensions are 75 mm x 25 mm, providing for a large area of sampling at a resolution of 50 nm/step. To enable efficient operation of an Orbitrap mass spectrometer, MALDI/ESI Injector is equipped with a computer-controlled pneumatic gate valve, which allows for rapid exchange of sample slides while keeping pressure of 2x10-10 mbar in the analyzer.
Shown in Figure 4, a UV laser beam is routinely focused to a spot of 20 µm in diameter. In MALDI mode, a diode-pumped solid state YAG laser is employed. Laser parameters are the following: single mode, an output energy of 20 µJ, 2 mrad beam divergence, 1 mm beam diameter at laser aperture, a wavelength of 355 nm, a user-defined repetition rate of 200 Hz to 2 kHz.
Figure 4: Focused Laser Spots

Lipids

Figure 5 shows signals obtained with a rat brain tissue sample. Experimental setting: negative ion mode, 60,000 mass resolution, 30 µm spatial resolution, acquisition rate of 7.2 pixels/s. 147,508 pixels, 349 nm laser wavelength, 2 µJ laser energy.
Images at the bottom panel of Figure 5 demonstrate spatial distributions of the two closely spaced in m/z domain (δm = 50 mmu) lipid molecules.
Figure 6 shows data obtained with a mouse kidney tissue at 100 µm step size, 120,000 mass resolution (256 ms transient), 32767 pixels, and an acquisition rate of 3.2 pixels/s.
Figure 5: Imaging of Rat Brain Tissue
Figure 6: Drug Localization in Mouse Kidney Tissue

Peptides and Proteins

Spectroglyph provides a complete unsurpassed solution for EP MALDI imaging with an OrbitrapTM Mass Spectrometer at high spatial and mass resolution, < 20 µm and 240,000, respectively.

Figure 7 shows signals of 1 pmol Bovine Serum Albumin (BSA) tryptic digest obtained with a Q Exactive Mass Spectrometer.
Figure 7: EP MALDI spectrum of 1 pmol BSA Tryptic Digest.
Table 1: Identifications of peptides from EP MALDI spectrum in Figure 7.

Figure 8 shows EP MALDI signals of 1 pmol intact protein samples. Upper panel - insulin chain B, bottom panel - thymosin β4.

Figure 8: EP MALDI signals of Intact Proteins. Upper panel - insulin chain B, bottom panel - thymosin β4

Contact Us

Due to proven performance enhancing capabilities, MALDI/ESI Injector has already received attention in the imaging field. Interested customers and distributors can contact us for a quotation by writing to info@spectroglyph.com


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