[Histonet] Re: paraformaldehyde grade

[David A. Wright]

Hi Mary, René, & Histonet

I agree with René completely about concentration & different
paraformaldehyde grades but you might want to consider a
couple of other issues too:
a) physical state.  A coarse prill is much easier to weigh out
without contamination than a fine powder.
b) filtration.  Before perfusing the brains you have to filter
out anything that might clog the capillaries. There's usually
a milky haze left after dissolving the paraformaldehyde which
you have to remove.  I imagine that a lower grade might have
more undissolved matter, and you have to change filters a lot
even with good stuff (approx every half liter).
-David
------
David A. Wright PhD
University of Chicago Section of Neurosurgery

---- Original message ----
>Date: Thu, 11 Sep 2008 12:09:50 -0500 (CDT)
>From: histonet-request <@t> lists.utsouthwestern.edu  
>Subject: Histonet Digest, Vol 58, Issue 13 Message: 1
>Date: Wed, 10 Sep 2008 10:10:42 -0700 (PDT)
>From: Rene J Buesa <rjbuesa <@t> yahoo.com>
>Subject: Re: [Histonet] Paraformaldehyde
>To: histonet <@t> lists.utsouthwestern.edu, "Mary P. Brownson"
>	<mpb1211 <@t> uwyo.edu>

>
>It does not really matter, BUT it will have to be taken into
consideration when calculating the final concentration you
want to use.
>René J.
>
>--- On Tue, 9/9/08, Mary P. Brownson <mpb1211 <@t> uwyo.edu> wrote:
>
>From: Mary P. Brownson <mpb1211 <@t> uwyo.edu>
>Subject: [Histonet] Paraformaldehyde
>To: histonet <@t> lists.utsouthwestern.edu
>Date: Tuesday, September 9, 2008, 4:50 PM
>
>Hello,
>
>I plan to use paraformaldehyde for perfusion of rat brains. 
My question
>is; what grade paraformaldehde should I be using?  Reagent
grade, 95% or
>other?  Or does it not matter?
>

>Thank you,

>Mary Brownson
>School of Pharmacy
>University of Wyoming
>Laramie, WY 82070
>mpb1211 <@t> uwyo.edu