PI concentration
Ken Hook (hookk@aa.wl.com)
Tue, 01 Apr 1997 16:19:01 -0500 (EST)
Why would 20 ug/ml propidium iodide vs 50 ug/ml not make much difference in the
G1 CV on a FACScan but a fairly large difference on an Elite? The CV's are
usually 5% or higher on the Elite at the lower PI concentration but comparable
to the FACScan at the higher concentration. Furthermore, Vindelov's staining
works well on the FACScan but EtOH-fixed cells have the best CV's on the Elite
(both with 50 ug/ml PI). The air-cooled lasers have similar outputs. Bead
CV's are comparable. Could it have something to do with the longer (30 cm or
so) sample tube on the Elite causing some sort of dye equilibrium effect? On
the Elite there is a well-documented drift in the fluorescence for the first
minute or so after putting the tube on, but I can tell from a plot of time vs
red Fl that I'm past the drifty part.
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