[Nhcoll-l] FW: Telling formalin from ethanol

[Robert Waller]

Hi Megan,

I like Dries’ idea of using floatation of a piece of paper for
distinguishing ethanol rich solutions from more water-based solutions –
seems very elegant.  Still, this test does may not exactly respond to the
question you put forward.  The test method you adopt may depend on how you
want a solution that is (for example) 3% formalin and 50% ethanol to be
identified.  The paper sinking test would (I suspect) lead to this being
identified as an ethanol solution.  If you would prefer this to be
identified as a formalin solution then you need to employ a test based on
the positive identification of formaldehyde.

 

As Elizabeth says, a problem for distinguishing ethanol from formalin
solutions is that residual formalin from fixation will make many ethanol
solutions test positive for formaldehyde if sensitive tests are applied.
Don McAllister and I developed a test strip for distinguishing formalin from
ethanol solutions that we deliberately made less sensitive to avoid that
problem.

 

It has been published as:

Robert Waller and D.E. McAllister. A spot test for distinguishing formalin
from alcohol solutions.  Proceedings of the 1985 Workshop on the Care and
Maintenance of Natural History Collections, J. Waddington and D.M. Rudkin,
Eds., 93 99, 1986.

and Curator 30(3), 240-249, 1987.

 

Rob

 

From: nhcoll-l-bounces at mailman.yale.edu
<mailto:nhcoll-l-bounces at mailman.yale.edu>
[mailto:nhcoll-l-bounces at mailman.yale.edu] On Behalf Of Dietrich, Elizabeth
Sent: March 6, 2014 9:32 AM
To: 'Best, Megan'; 
Subject: Re: [Nhcoll-l] Telling formalin from ethanol

 

Something to keep in mind-

Based on our sampling, by chemical analysis, of fluids in tanks of preserved
animals, if the animals were fixed or previously preserved in formalin there
will always be a significant amount present in the alcohol.  By significant,
I don’t mean by quantity but as a hazard.  I would caution against doing
much sniff testing.

 

From: nhcoll-l-bounces at mailman.yale.edu
<mailto:nhcoll-l-bounces at mailman.yale.edu>
[mailto:nhcoll-l-bounces at mailman.yale.edu] On Behalf Of Best, Megan
Sent: Thursday, March 06, 2014 9:03 AM
To: nhcoll-l at mailman.yale.edu <mailto:nhcoll-l at mailman.yale.edu> 
Subject: [Nhcoll-l] Telling formalin from ethanol

 

Hello all,

I’ve been benefitting from the conversations on this listserv for some time
now, really fascinating and useful stuff.  I manage a research collection,
mostly of marine invertebrates, and I have a question:

Is there an easy way to tell if a fixative is formalin or ethanol?  Aside
from the smell test!  I’m looking to organise hundreds of jars from various
benthic surveys, and we want to switch out anything that’s in formalin to
ethanol.  The formalin is buffered so I don’t think a pH difference would be
a strong indicator.  Any ideas/advice would be appreciated.

-Megan

Megan Best
Invertebrate Taxonomy
tel: 902.426.2791   email: megan.best at dfo-mpo.gc.ca
<mailto:megan.best at dfo-mpo.gc.ca> 
Ocean and Ecosystem Sciences Division | Division des sciences de
l'écosystème et de la mer
Department of Fisheries and Oceans | Ministère des Pêches et Oceans
Government of Canada | Government du Canada
Bedford Institute of Oceanography | Institut Océanographique de Bedford

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