Fig. 18 The difference in the ion map between norharmane and DHB matrix. The structures visible with the DHB matrix are not present when the norharmane matrix is used. Cresyl violet staining show white and gray matter in the spinal cord slices.
From 11 peaks taken for the analysis, three behaved in that way: in DHB, they can be seen in the white or gray matter, whereas in norharmane their distribution is over the whole tissue (m/z = 766, 810, and 872). Surprisingly the ion at m/z=798 in the norharmane matrix shows its distribution in a gray region only. Because of that, the norharmane matrix seems sufficient for the lipids when the differences among the structures are not crucial.
The study of the DAN matrix revealed that the way of sample preparation (the number of matrix layers and the spraying nozzle height) – may also influence the overall picture. In the case of this matrix, three ions: m/z 760, 798, 868 were detected from the gray matter - not from the whole tissue as in the case of the “classical” DHB matrix (see Fig. 19).