[NHCOLL-L:3742] Dealing with formalin precipitate

[Geoff Read]

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


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 Geoff Read <g.read at niwa.co.nz>
   http://www.annelida.net/
  http://www.niwascience.co.nz/ncabb/