Re: 4% PFA/PBS

From:"J. A. Kiernan"

I was about to write a long answer to your
questions, but then saw one from Fred Monson
that said it all. All I can add is to emphasize
the point that there is no such thing as a
solution of paraformaldehyde. The fixative
agent is formaldehyde. There is plenty of
printed literature in textbooks and in 
peer-reviewed journals. If Fred's reply
does not adequately answer your question,
and if you don't have a nearby library, go to
the HistoNet Archives at
and you will find lots of good stuff about the
various names and states of formaldehyde. 
John A. Kiernan
Department of Anatomy and Cell Biology
The University of Western Ontario
London,   Canada   N6A 5C1
"Atoska S. Gentry" wrote:
> Dear All, will someone please provide me information on the shelf life of
> 4%PFA/PBS?  I have a few liters of this unused fixative left over from
> various experiments.  And I'm wondering if it can be used for routine
> fixation or if I should just treat it for waste disposal?  A couple of
> years ago I heard by word of mouth that after a certain period of time the
> PFA reverts back to  regular formaldehyde.  Does anyone have a reference
> you can recommend whereby I can get my questions answered?  On the other
> hand if you know for a fact that it can be used as  either formaldehyde or
> 10% formalin please will you share this info with me?  If it can be used
> does it need to be stored at 4C?  Thanks, Atoska
> Atoska S. Gentry B.S., HT(ASCP)
> Research Assistant III
> Scott-Ritchey Research Center
> College of Veterinary Medicine
> Auburn University, AL  36849
> Phone# (334)844-5579  Fax# (334)844-5850

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