[NHCOLL-L:3744] Re: Dealing with formalin precipitate

[John E Simmons]

Geoff,
You are probably right that it is paraformaldehyde, but it could also be a
buffer precipitating out of solution (depending on what buffer you use).  If
it is paraformaldehyde, you should be able to dissolve it by gently warming
the solution or by adding some NaOH.  Before you try either of these
remedies, I recommend you contact Simon Moore, who has resolved several
similar problems with invertebrate specimens encased in precipitates before
and would probably share his procedures and experience with you.  Simon is a
conservator with the Museums & Archives Service of the Hampshire County
Council, UK.  His email address is:  simon.moore at hants.gov.uk

Please send the list a follow-up post and let us know what procedure(s) you
followed and how well they worked.

--John

John E. Simmons
Museologica
1528 ½ Puddintown Road
State College, Pennsylvania 16801
simmons.johne at gmail.com
303-681-5708


On Feb 7, 2008 12:55 AM, Geoff Read <g.read at niwa.co.nz> wrote:

> Dear Colleagues,
>
> Some marine worms I am identifying are in glass vials of 10% formalin in
> which a large amount of white precipitate has formed, thus encasing and
> adhering to the animals, rendering them more or less unidentifiable or
> damaged when broken out of the precipitate, particularly when quite small.
>  I asssume this precipitate is paraformaldehyde, even nastier to deal with
> than formalin itself.  I have never encountered this phenomenon to this
> excessive degree before in little vials, and don't have the details of how
> the original fixative solution was prepared or whether it was buffered. The
> samples are about a year old and have not been excessively cooled as far as
> I know.
>
> Can anyone suggest how to dissolve the precipitate? Normally I simply
> transfer the worms to 60% ethanol for storage.
>
> Geoff
>
>
> --
>
>  Geoff Read <g.read at niwa.co.nz>
>   http://www.annelida.net/
>  http://www.niwascience.co.nz/ncabb/
>
>
>


--
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.yale.edu/mailman/private/nhcoll-l/attachments/20080207/f27b8279/attachment.html