[Histonet] paraformaldehyde autofluorescence

[Gayle Callis]

Helen,

It is not the heat used to dissolve paraformaldehyde that causes 
autofluorescence, it is caused by aldehyde induced autofluorescence when the 
PFA crosslinks proteins.  There are places to buy PFA in liquid form to 
avoid having to weigh and dissolve.  We never bother to add NaOH if we heat, 
and we also buy our paraformaldehyde from Sigma.

We always heat our PFA but never exceeding 60C.  It will go into solution 
around 56C, with stirring in approx 15 minutes or so.

I suggest you (and the researcher) read about on autofluorescence on the 
IHCWorld website.  There is a superb discussion on both fluorescence and 
autofluorescence there.

Gayle Callis
HTL/HT/MT(ASCP)
Bozeman MT


----- Original Message ----- 
From: "Helen Beard" <hbeard27 <@t> hotmail.com>
To: <histonet <@t> lists.utsouthwestern.edu>
Sent: Tuesday, March 18, 2008 6:45 PM
Subject: [Histonet] paraformaldehyde autofluorescence



We have been stirring pfa overnight @RT to dissolve, avoiding heat, as one 
of our researchers believes heating to 60-65C causes autofluorescence in 
tissue.  Has anyone had this problem with autofluorescence? I would prefer 
to heat and add NaOH. Also what are thoughts on using fresh, frozen 4%pfa?
Thanks in advance

Helen Beard
Adelaide South Australia
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