Re[2]: Paraformaldehyde fixative

/G=Gerhard/S=Nebe-von-Caron/OU=1890CHPE/O=TMGB.URC/@LANGATE.gb.sprint.com
Fri, 3 May 1996 05:19:00 -0400

As said in another message, this comes up again and again.
Paraformaldehyde are 'chains' of formaldehyde which is
normally created by boiling paraformaldehyde, thus heating
also dissolves it in water. With time it can turn into formic
acid, thus to stabilize formaldehyde solutions approx. 15%
methanol is added which is what one commonly buys as formalin
solution.

Gerhard Nebe-v.Caron Unilever Research, Colworth Lab.
Sharnbrook, Beds. GB-MK44 1LQ Tel.:+44(0)1234 222066
Fax.: 222344 Gerhard.Nebe-von-Caron@unilever.com

______________________________ Reply Separator
_________________________________ Subject: Re: Paraformaldehyde
fixative Author: rmoldwin@midway.uchicago.edu at INTERNET Date:
02/05/96 23:29

At 09:17 AM 4/29/96 EST, you wrote: >First, make it fresh. I make a
fresh batch each week and store @ 4C. >For 2% I dissolve 2g
paraformaldehyde in 75 mL PBS, add a few drops of 5M KOH >until
dissolved, adjust pH to 7.0 with HCl. >Daniel >CDC

I've read this in several places, that one must make fresh PF
solutions. I have used 2% PF in PBS over a year old (stored dark at
4C) and have not noticed any problems. I have also analyzed samples a
month or two after fixing without problems, and no apparent signal
(FITC) degradation. Is there any hard data that shows that PF
solutions go bad? If so, what happens to it? Is there any reference
for this?

--Rich ^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^
Richard Moldwin, M.D., Ph.D. Section of Pediatric Hematology/Oncology
University of Chicago Hospitals Wyler Room C408, MC 4060 5841 S.
Maryland Ave. Chicago, IL 60637

E-mail: rmoldwin@midway.uchicago.edu WWW:
http://rmoldwin.bsd.uchicago.edu Phone 312-702-6808 Fax
312-702-9881


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