ig. 1. Schematic illustration of a typical microprobe MSI experimental workflow. The frozen sample is cryosectioned and mounted on a suitable substrate. Following appropriate pretreatment (as dictated by the constraints of the ionization method and the sample at hand) the microprobe is sequentially rastered across the sample surface, generating a pixelated array of position-specific mass spectra. Using MSI software packages, individual ion abundances are plotted as a function of their location, generating a false color map that corresponds to the chemical distribution across the sample.