Re: [Histonet] low temp thermometer

From:"Karen Weidenheim"

Dear Steve, I presume you are freezing muscle biopsies, or possibly
research material.
This isopentane/liquid nitrogen method is more an art than a science. 
Altitude of your lab and humidity of your ambient air, are the 2 major
limiting factors.  The most important thing in the freezing is not
measuring the temperature but rather visual assessment of the state of
the isopentane.  We put the isopentane in a 250 ml stainless steel
beaker and lower it slowly into the liquid nitrogen.  We wait to freeze,
until the isopentane has formed ice all around the walls of the beaker
and all the way up the wall of the beaker, and completely across the
bottom of the beaker.  It will be syrupy.  We use 25 seconds of freezing
(I know the books say 5-10 seconds).
Our lab is at sea level.  It is also often humid here.  We discard the
isopentane every 3 months when there is no major humidity and more often
(every 6 weeks) when we have a run of humid weather, or when we have a
problem with freezing artifact, or when I think my assistant has been
sloppy with its storage.
We keep the beaker very clean i.e. we scour with steel wool.  We make
sure there is no residual water in the beaker (I keep 2 beakers so one
is freshly clean and dry at all times).
I have not used the thermometer since I was a young attending a long
time ago!!!

Karen M. Weidenheim, M.D.
Professor of Pathology, Clinical Neurology and Clinical Neurosurgery
Albert Einstein College of Medicine
Chief, Division of Neuropathology
Montefiore Medical Center
111 East 210th Street
Bronx, NY   10467 
(718) 920-4446
FAX (718) 653-3409
Beeper (917) 556 3696
CONFIDENTIALITY NOTICE:  This email, including any attachments, is for
the sole use of the intended recipient(s).  The information contained in
this message may be private and confidential, and may also be subject to
the work product doctrine.  Any unauthorized review, use, disclosure or
distribution is prohibited.  If you are not the intended recipient,
please contact the sender by reply e-mail and destroy all copies of the
original message.  Thank you.

>>> Steven Coakley  7/14/2005 12:07:15 PM >>>
We're doing allot of liquid nitrogen/isopentane snap freezing and I'd
like to purchase a good low temp thermometer.  Any suggestions or advise
out there?

 Start your day with Yahoo! - make it your home page 
Histonet mailing list

Histonet mailing list

<< Previous Message | Next Message >>