Development of a stigmatic imaging mass spectrometer using laser desorption/ionization

Imaging mass spectrometry based on matrix-assisted laser desorption/ionization gives distributions of multiple biomolecules and identification of analytes in a tissue section. We are developing a stigmatic imaging mass spectrometer using a multi-turn time-of-flight mass spectrometer, MULTUM-IMG. A mesh pattern image was obtained with spatial resolution of 3 μm. Separation of stigmatic ion images according to the mass-to-charge ratio was also successfully demonstrated with the micro-dot pattern made with crystal violet and methylene blue. An ion image of a micro-dot pattern sample was observed after ten cycles in the multi-turn circuit of MULTUM-IMG, and the pattern of the sample was maintained. Then, stigmatic ion images of the ions of crystal violet and methylene blue produced from the stained section of a brain were observed. An ion image of whole part of a hippocampus (3.25 mm × 1.5 mm) in the brain section can be obtained within 13 minutes.