GNPS - High mass resolution lipid MALDI imaging of rat brain

Rat brain tissues for imaging mass spectrometry were removed from animal organs, frozen on dry ice, and then stored at -80-degree C until analysis. 10-micrometer rat brain tissues were sectioned using a Leica CM 3050S Research Cryostat (Leica Biosystems, Wetzlar, Germany), prior to thaw mounting onto indium tin oxide-coated microscope slides (Delta Technologies, Loveland, CO, USA). 1,5-diaminonaphthalene (DAN) MALDI matrix layer was sublimated to the microscope slide using an in-house sublimation apparatus. MALDI imaging mass spectrometry was performed on a 7T solariX Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with a dynamically harmonized ParaCell XR (Bruker Daltonics, Bremen, Germany). Analysis was performed in negative ion mode from m/z 400 to 2000 with ~0.5 s time-domain transient length, resulting in a resolution of ~35,000 FWHM at m/z ~760. The MALDI source is equipped with a Smartbeam II Nd:YAG MALDI laser and was used to sample at a pixel spacing of 100 micrometers in the x and y dimensions using 200 laser shots per pixel (large laser focus, 2 kHz frequency) with Smart Walk enabled.