[Histonet] Silly Question? - Need help quickly!

Rene J Buesa rjbuesa <@t> yahoo.com
Thu Dec 11 11:58:23 CST 2008

Methanal, which is the chemical name of formaldehyde, polymerizes. If it forms a polymer of at least 50 molecules or more, it gets solid = para-formaldehyde.
Formalin (a trade name as formol is also another trade name)is the 37-50% aqueous solution of formaldehyde (with some additiveses to prevent polymerization).
You can prepare BNF using the formalin solution or dissolving the amount of solid para-formaldehydede to get to the concentrationon you desire.
The chemical in both solutions is the same = methanal or formaldehyde.René J.

--- On Thu, 12/11/08, Weems, Joyce <JWeems <@t> sjha.org> wrote:

From: Weems, Joyce <JWeems <@t> sjha.org>
Subject: RE: [Histonet] Silly Question? - Need help quickly!
To: "Pat Flannery" <pjfnefro <@t> duke.edu>, histonet <@t> lists.utsouthwestern.edu
Date: Thursday, December 11, 2008, 12:12 PM

I was just going to post a question regarding paraformaldhyde myself!
Just last week I believe I remember someone saying that paraformaldehyde
and formalin are the same and they had put the same solution in two
different containers for one of their researchers because they were so
insistent to have two different solutions. Are they the same? 

Well, today I have a request to put tissue for a researcher in formalin
and paraformaldehyde. So.... Without percentage required, do I use 10%
NBF? Do I call somewhere and get paraformaldehyde and make 4%

I have asked the surgeon twice for the number for the lab so I can find
out - don't have it yet. I have two fresh adrenals in the fridge. Help!!

Thanks in advance... 

Joyce Weems 
Pathology Manager 
Saint Joseph's Hospital 
5665 Peachtree Dunwoody Rd NE 
Atlanta, GA 30342 
678-843-7376 - Phone 
678-843-7831 - Fax 


-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Pat
Sent: Thursday, December 11, 2008 11:59 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Silly Question?

Please humor me on this if it's obvious (to everyone but me):  why do we
use paraformaldehyde (which is so inconvenient to make up) rather than
buffered formalin or just diluted formaldehyde itself?

It seems that around here, some folks prefer paraformaldehyde (either 2%
or 4%) and others use formalin, while some others stick to diluted
formaldehyde (I see all 4 on labels for specimens submitted for
histology).  Is it mostly a matter of personal preference or where you
were trained (i.e. force of habit) or is there a valid reason to use
each solution (basically the same chemical once in solution, merely
buffered or not)?  The only answer I've gotten when I've asked is,
"That's what we always use."


-Pat Flannery (not a "real" histologist - I just play one in the lab)

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