[Histonet] quick question about formaldehyde

[Weems, Joyce]

Also, John said "formalin" - was the solution formalin or 37% formaldehyde  - without buffers? Would that make a difference? 

Joyce

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu]On Behalf Of Morken,
Tim - Labvision
Sent: Thursday, May 12, 2005 2:08 PM
To: 'John Kiernan'; Andrea Grantham
Cc: histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] quick question about formaldehyde


John,  you said "   Small amounts of methanol and formate ions are not going
to change the fixative properties."

But after 12 years  will it really be a "small amount?" How do we know what
percentage of the solution will have been converted? 

Tim Morken


-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of John Kiernan
Sent: Thursday, May 12, 2005 10:48 AM
To: Andrea Grantham
Cc: histonet <@t> lists.utsouthwestern.edu
Subject: Re: [Histonet] quick question about formaldehyde


Two things could have happened to unopened
formalin in 12 years:
1. Polymerization (to paraformaldehyde). This is
   evident as a white precipitate. It slightly
   reduces the concentration in the liquid,
   but that does not matter for fixation.
   Polymerization is accelerated by low room
   temperature, and it is claimed that the
   process can be reversed by autoclaving(paper
   in Stain Technol about 40 years ago).
2. Cannizzaro's reaction, in which 2 molecules
   of formaldehyde react together, producing
   one molecule each of methanol and formic
   acid. This happens in all formaldehyde solutions
   and causes lowering of the pH. This doesn't matter 
   if you make a neutral buffered fixative solution. 
   Small amounts of methanol and formate ions are not 
   going to change the fixative properties.
Bottom line: OK to use, but be sure to check the
pH of the working fixative solution and adjust if
necessary.
-- 
-------------------------------
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
   kiernan[AT]uwo.ca
   http://publish.uwo.ca/~jkiernan/
   http://instruct.uwo.ca/anatomy/530/index.htm
_______________________________
Andrea Grantham wrote:
> 
> One of the labs here is closing and they have a case of formaldehyde, 
> 37.5%, that they are trying to give away. They have had it in their 
> lab since 1993. The bottles have not been opened. Is it still good to 
> use? Andi 
> .....................................................................
> : Andrea Grantham, HT(ASCP)     Dept. of Cell Biology & Anatomy     :
> : Sr. Research Specialist       University of Arizona               :
> : (office:  AHSC 4212)          P.O. Box 245044                     :
> : (voice:  520-626-4415)        Tucson, AZ  85724-5044    USA       :
> : (FAX:  520-626-2097)          (email:  algranth <@t> u.arizona.edu)       :
> :...................................................................:
>            http://www.cba.arizona.edu/histology-lab.html
> 
> _______________________________________________
> Histonet mailing list
> Histonet <@t> lists.utsouthwestern.edu 
> http://lists.utsouthwestern.edu/mailman/listinfo/histonet

_______________________________________________
Histonet mailing list
Histonet <@t> lists.utsouthwestern.edu
http://lists.utsouthwestern.edu/mailman/listinfo/histonet

_______________________________________________
Histonet mailing list
Histonet <@t> lists.utsouthwestern.edu
http://lists.utsouthwestern.edu/mailman/listinfo/histonet


Confidentiality Notice ** The information contained in this message may be privileged and is confidential information intended for the use of the addressee listed above. If you are neither the intended recipient nor the employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any disclosure, copying, distribution or the taking of any action in reliance on the contents of this information is strictly prohibited. If you have received this communication in error, please notify us immediately by replying to the message and deleting it from your computer.
Thank you. Saint Josephs Health System, Inc.