<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">Hi Dave <div>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 </div><div>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.<br><br><div dir="ltr">With all good wishes, Simon Moore. <div>Sent from my iPhone</div><div><br></div></div><div dir="ltr"><br><blockquote type="cite">On 11 May 2023, at 17:34, David Boyd <dboyd10@lsu.edu> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
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<p class="MsoNormal">Hello all,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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’
<i>Herpetological Collecting and Collections Management</i> 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.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks in advance,<o:p></o:p></p>
<p class="MsoNormal">Dave<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;mso-ligatures:none">David A. Boyd, MSc<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;mso-ligatures:none">Collections Manager, Ichthyology and Herpetology<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;mso-ligatures:none">Louisiana State University Museum of Natural Science<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;mso-ligatures:none">119 Foster Hall, Baton Rouge, LA 70803<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;mso-ligatures:none">(225) 681-0456</span><span style="mso-ligatures:none"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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