[Histonet] RE: pfa vs. formalin

[Bryan Hewlett]

Hi Paul,

Actually, commercial formaldehyde solutions may contain anywhere from 5-15% 
methanol.
It often depends on geographic location and what time of year the reagent is 
shipped.
Over the years, I have performed many side-by-side studies of 4% phosphate 
buffered formaldehydes,
prepared from both commercial formaldehyde solutions and from 
paraformaldehyde.
The fixatives were used for a wide range of investigations including 
morphology using routine oversight and many special stains,
histochemistry, IHC, ISH and EM.
In NO case could I or anyone else detect any difference
Are you aware of any definitive studies which prove that the presence of 
0.5-1.5% methanol is deleterious for any investigation?

Regards,

Bryan



----- Original Message ----- 
From: "Monfils, Paul" <PMonfils <@t> Lifespan.org>
To: <histonet <@t> lists.utsouthwestern.edu>
Sent: Friday, August 04, 2006 2:36 PM
Subject: RE: [Histonet] RE: pfa vs. formalin


> The only difference is that commercial formaldehyde solution contains a
> stabilizer, usually 10 to 15% methanol.  Therefore, 10% NBF made up from
> such a solution contains 1 to 1.5% methanol, while 10% buffered NBP 
> contains
> nothing but water, formaldehyde, and buffer salts.  For routine
> morphological studies this makes no difference whatsoever.  But for some
> special studies the presence of a small amount of methanol could be
> deleterious, and for any such procedures paraformaldehyde would be
> preferable.
>
>
>
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