From: /G=Gerhard/S=Nebe-von-Caron/OU=1890CHPE/O=TMGB.URC/@LANGATE.gb.sprint.com
Date: Wed Nov 22 1995 - 07:51:00 EST
The degrading product is formic acid if I remember right.
This is why some commercial solutions contain about 10 to
15% alcohol for stabilisation. This is probably why it is
sometimes difficult to reproduce someone else's fixation
protocol were either the acid or the alcohol was important
for the process. It is also worthwhile to consider the
osmotic strength of your solutions to make the cells look
happy when they go.
Gerhard Nebe-v.Caron
Unilever Research, Colworth Laboratory Sharnbrook,
Bedfordshire
GB - MK44 1LQ
Tel: +44(0)1234-222066
FAX: +44(0)1234-222344
E.mail: gerhard.nebe-von-caron@urcgb.sprint.com
______________________________ Reply Separator _________________________________
Subject: Re: paraformaldehyde or formaldehyde?
Author: bakkea@ohsu.edu at INTERNET
Date: 21/11/95 21:21
Jim Kiss asked: so Why do we bother with paraformaldehyde.
Formaldehyde is not stable forever. It can be purchased as EM
grade in small, sealed aliquots. When exposed to air it begins to
oxidize. The stock solution is probably good for 6 months, although
I don't have exact data on that. The working dilution is only good
for 1-2 weeks, although for some purposes, like standard surface
markers that are bright, it will work for a month.
Paraformaldehyde is a solid form that is stable as a solid and can
be made up fresh as formaldehyde to use. Paraformaldehyde is
considerably cheaper, but requires the hassle of working with a
chemical hazard when making the solution. As a solution it has the
same stability as formaldehyde.
Tony Bakke
(bakkea@ohsu.edu)
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