[Nhcoll-l] Paraformaldehyde for whole specimen fixation

[Simon Moore]

Hi Dave 
There used to be a yellow powder called Dowicil which readily dissolved in fresh or marine water and which released formaldehyde in the presence of protein 
I tested it in 1970 (!) and it gave good results at 10’/. concentration. Unsure if it’s available or if anyone else might have tried it more recently- produced by Dow chemicals.

With all good wishes, Simon Moore. 
Sent from my iPhone


> On 11 May 2023, at 17:34, David Boyd <dboyd10 at lsu.edu> wrote:
> 
> 
> 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
>  
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