sort purity

Michael Fox MFox at
Wed Jan 19 10:55:56 EST 1994

In regard to your sorting purity problem, there are several possibilities 
that may be affecting your results.  First, do you get essentially 100% 
purity when you sort beads instead of cells?  If so, then the sorting is 
probably working properly.  Are you running the sample through at a very high 
rate?  This would affect sorting purity, if you are getting a lot of 
coincidences, even if you are trying to correct for them.  Are your cells 
very large?  Large cells disrupt the droplet formation (see article by 
Harkins and Galbraith, Cytometry 8:60-80 (1987), and can dramatically affect 
sorting purity.  Finally, if you are gating the population through a series 
of gates, be aware that you have to mimic all of the collection gates with 
sort gates.  If you are just setting sort gates on the final gated 
population, the sorted population will not be gated on any of the other gates 
you set.  This can lead to large errors.  Many instrument manufacturers do 
not point this out very clearly, if at all.

Good luck.

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