[Nhcoll-l] Paraformaldehyde for whole specimen fixation

[David Boyd]

Hello all,

Our lab wants to explore the use of paraformaldehyde as a whole-specimen fixative, to be carried as a dry powder to locations where formalin cannot be obtained. Simmons' Herpetological Collecting and Collections Management describes two major disadvantages of solid paraformaldehyde: 1) it is extremely alkaline in solution, to the point that it may cause specimens to clear, and 2) it does not dissolve readily and requires some effort and boiling water to form a solution of appropriate concentration for fixing specimens. The same work also details a 1989 protocol by Ehmann to mitigate these issues through addition of anhydrous sodium bicarbonate, a wetting agent, and citric acid powder.

Can anybody vouch for Ehmann's method or offer other tips or tricks for buffering and dissolving paraformaldehyde to ensure quality (fish) specimens? I doubt there is enough demand for any supplier to offer premixed, neutrally-buffered powders-but if you know of one, please let me know.

Thanks in advance,
Dave

David A. Boyd, MSc
Collections Manager, Ichthyology and Herpetology
Louisiana State University Museum of Natural Science
119 Foster Hall, Baton Rouge, LA 70803
(225) 681-0456

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.yale.edu/pipermail/nhcoll-l/attachments/20230511/381e4adf/attachment.html>