[Histonet] paraformaldehyde in the microwave

John Kiernan jkiernan <@t> uwo.ca
Fri Jan 13 00:54:02 CST 2006

The source of heat does not matter.
Paraformaldehyde depolymerizes at 60C in the
presence of a base such as disodium hydrogen
phosphate. It won't depolymerize ("dissolve") when
heated in pure water. 

This information is present in every
histotechnical textbook published since about
1960. The chemistry is very simple, and abundantly
available on the internet. Paraformaldehyde and
formalin are sources of hydrated formaldehyde,
which fixes tissues well if used at approximately
neutral pH for 12-24 hours.

John Kiernan
London, Canada.

Michael Doube wrote:
> Hi there
> It's been a while since I last made 4% paraformaldehyde in
> phosphate-buffered saline - it was a few years back as an undergrad.
> This time I'm in a new lab, and found that there is no hotplate!  So,
> after trying to keep the suspension warm with hot water baths (tedious)
> , I resorted to the microwave, on low power.  It seems to work much
> faster than what I remember with the conventional technique.  Has anyone
> had any experience with this?
> Mike
> --
> Michael Doube  BPhil BVSc MRCVS
> MPhil / PhD Student
> Dental Institute
> Barts and The London School of Medicine and Dentistry
> Queen Mary, University of London
> New Rd
> London  E1 1BB
> United Kingdom
> Phone +44 (0)20 7377 7000 ext 2681

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