Microscopic images, analysis glass slide

The individual drop-by-drop analysis started with microscopic obsers at ion several decades ago. The method is tedious and sometimes erroneous, such as when big drops are flattened in-between glass slides, or when the held depth is so small that the adjustment of the image plane cuts the drop above or below its equator, resulting in an apparent smaller Size. Hiesc problems were not amenable to ready solution with the arrival of shape recognition software in the l980s. 

DESI, an ionization technique developed by Cooks and coworkers [88] can be used for IMS analysis under atmospheric pressure with minimal sample preparation [89] (see Section 2.5.2). Eor DESI imaging, the sample is either placed onto a target (e.g., microscope glass slide) or analyzed in situ [12]. A lateral resolution of 40 pm could be achieved by DESI [90]. 

In typical DESI imaging experiments, the collected tissue sample is flash frozen in liquid nitrogen and subsequently cut in micron thin sections using a cryostat-microtome the thin tissue slices are thaw mounted onto glass microscope slides for analysis the ions generated by the DESI (Chapter 2) are transported fi om surfaces to the gas phase for mass analysis as the surface is being moved in order to cover the entire sample area a mass spectrum is acquired for each pixel on the surface and finally, tissue images are constructed to display the spatial intensity distribution of individual selected lipid ion. 

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