Imaging Mass Spectrometry

This field really seems to be taking off these days.  It is especially interesting to see so many different approaches to the problem.  MALDI, DESI, electrospray, fs IR laser desorption, etc etc.  There is a big push these days to improve the spatial resolution from 100 microns to 10 microns to 1 micron.  For us SIMS users, our main niche has been submicron spatial resolution with depth profiling capabilities – traits which none of the other methods can provide.  With an effort to improve the spatial resolution, we are getting some pretty stiff competition.  There is a nice recent paper where 7 micron resolution is claimed for MALDI in atmospheric pressure.  Since many groups are getting serious about this sort of thing, I think they need to seriously consider more rigorous methods of evaluating spatial resolution.  For SIMS, we usually look at a sharp edge and measure the 80-20 distance.  So far, the other people are looking at their images and guessing.  How about some better protocols for this type of thing?