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Many years ago, I performed an experiment with a FACScan that sup-
ports Matt's hypothesis that viscous fluids may not flow as readily through
the flow cytometer. My "viscous solution" was detergent-solubilized nuclei
from the Jurkat cell line, stained with propidium iodide. The stock solution
was fairly concentrated, as I recall -- perhaps 10 million cells/ml. I did
not have the means for measuring the viscosity of this solution. I tried
this at full strength and at various dilutions. I weighed the tubes on an
analytical balance, ran them on the FACScan for five minutes, and weighed
them again. I used the low flow rate, which pumps 12 microliters/minute
when the sample tube contains just plain water. Over the course of the
five minutes, I watched the acquisition event rate in order to be sure that
any drop that I might see in the *mass* flow rate (microliters/minute) was
not the result of temporary clogs in the sample injection tube. I think
that I did get such clogs at the higher cell concentrations. However, even at
the lower concentrations, there was clearly a drop in the mass of liquid
transferred, even when there were no hiccups detectable in the event rate.
Hope that helps!
- John Ladasky
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CD-ROM Vol 3 was produced by Monica M. Shively and other staff at the
Purdue University Cytometry Laboratories and distributed free of charge
as an educational service to the cytometry community.
If you have any comments please direct them to
Dr. J. Paul Robinson, Professor & Director,
PUCL, Purdue University, West Lafayette, IN 47907.
Phone: (765)-494-0757;
FAX(765) 494-0517;
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