[Histonet] (para)formaldehyde (was: in situ question)

[Mikael Niku]

This has probably been discussed 1000s of times, but....

I'm wondering to what extent dissolved paraformaldehyde really is equivalent
to 4% formaldehyde or 10% formalin.
In my experience, samples fixed in formalin and "4% PFA" as we tend to say
are different when one does immunostaining or especially in situ
hybridization. Formalin is of course traditionally used in pathology,
whereas many labs doing immunos or ISH use "PFA".

But what really causes the differences? Is it incomplete de-polymerization
of paraformaldehyde, or perhaps the methanol typically included in formalin?

-----------------------------------------------------
 Mikael Niku, PhD, university lecturer            
 University of Helsinki, Division of Nutrition
 URL: mikael.nikunnakki.info

 - What do I think of western civilization?
   I think it would be a good idea!                       
                                            Gandhi
-----------------------------------------------------
-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Tony Henwood
Sent: 20. elokuuta 2008 4:42
To: Lee Crosby; histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] in situ question

Which the becomes 4% formaldehyde or equivalent to 10% formalin. Not 4%
paraformaldehyde.

Regards

Tony Henwood JP, MSc, BAppSc, GradDipSysAnalys, CT(ASC) Laboratory Manager &
Senior Scientist
Tel: 612 9845 3306
Fax: 612 9845 3318
the children's hospital at westmead
Cnr Hawkesbury Road and Hainsworth Street, Westmead Locked Bag 4001,
Westmead NSW 2145