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I've been the operator of a FACStar Plus for a little over a year now
doing quite a bit of cell sorting. Have you ever started setting up for a sort
and took a quick measurement of the droplet break-off, then slosh the sheath
tank to find out that you're low; then filled it up again, taking another
measurment of the droplet break-off to find out it changed? Well this got me
thinking (ouch that hurts!), that the "sheath pressure" LED display is actually
the gas pressure of nitrogen going to the tank, not the liquid prssure leaving
the tank. I put a pressure gauge, low accuracy, on the liquid side to find a
difference of approx. 0.5 psi. (1L v.s. 5L) using the standard 5L tank. This
problem became more apparent when I went to my 20L sheath tank (a used soda can
works great) for sorting with the larger nozzles. It had a pressure difference
of approx. 2 psi. (1L v.s. 20L). This amount of pressure difference should have
very little effect on short sorts (say THAT three times fast!) under 2 hours
using nozzles under 100 microns, but what about the long sorts where < 1 % of
cells are sorted, where everything matters?
I am currently considering purchasing a "liquid" pressure regulator 0-25
psi. +/- 0.1 psi. with a high accuracy pressure gauge from ITT Conaflow. If
anyone has already done this type of upgrade, please let me know.
P.S. Do I need to go to BDIS and show them how to make a "constant
flow" cytometer or what?
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Jim Henthorn (405)271-2035 (voice)
The University of Oklahoma (405)271-3191 (FAX)
Oklahoma Center for Molecular Medicine
P.O. Box 26901, Room 309 BSEB
Oklahoma City, OK 73190 jim-henthorn@uokhsc.edu (e-mail)
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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;
Web
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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;
Web