[NHCOLL-L:5591] Re: PREFER as an alternative fixative to Formalin

[John E Simmons]

I have not used PREFER solution myself, but there are several reasons why
you should be very cautious about doing so.

The problem with most formaldehyde alternatives is that the solutions have
proprietary components, which means that you don't know what chemicals you
are using to preserve your specimens--this is analogous to having an
uncontrolled variable in an experiment (in other words, not a good idea).
According to the MSDS, Prefer is an aqueous solution of an unknown ratio of
glyoxal, ethanol, and a secret buffer.  You don't know if the ehtanol was
denatured or not (probably not) but without knowing what the buffer system
is, you have no way of knowing how it will behave long-term (is it stable?
Is it prone to oxidation or reduction?).  Because the ratio of the
components is unknown, you have to worry that it could be very high in
alcohol, which would dehydrate your specimens, or it could be overloaded
with buffer and cause post-fixation preservation problems, etc.  According
to the MSDS, the pH of PREFER is 3.75 to 4.25, which is okay for fixing a
biopsy sample but far too acidic for long-term specimen preservation.  Not
knowing what buffer system PREFER uses, you run the risk of further
complications if you try to buffer it to close to neutral yourself.

Glyoxal itself (formula OCHCHO) is an aldehyde similar to formaldehyde, used
in industry to cross-link proteins and collagen, so its fixative action is
likely to be very similar to that of formaldehyde, but probably has much
less ability to penetrate tissues.  One of the great advantages of
formaldehyde over all other aldehyde fixatives is how deeply and how quickly
it penetrates tissues.  However, Prefer solution is marketed specifically
for fixing biopsy samples, which are very small tissue blocks.  There are
dozens of great histological fixatives that work well on tissue blocks under
a cubic cm that are completely unsuitable for larger specimens because of
their inability to penetrate deep tissue blocks or to penetrate rapidly
enough to fix them.

Another potential serious drawback to glyoxal is its density (1.27 g/cm3),
which is much greater than that of formaldehyde (0.8153 g/cm3) so your
specimens are probably going to float in it rather than be submerged, which
will make thorough fixation of a fish very difficult to do.  According to
the MSDS, the specific gravity of PREFER is 1.003,which can still cause
problems (and it is hard to evaluate this number because the ratio of the
components is proprietary).

If you are preserving fish for classroom use or exhibit use, then the use of
a proprietary formula could be justified.  However, if you are preserving
fish for scientific collections, I caution against using unknown chemicals
that might well affect the long-term stability of the specimens or affect
the ability to later chemical analysis of the specimen, DNA extraction, etc.

If you do try PREFER solution, please write up your results and let us all
know how it goes.  There is a great need for a better alternative to
formaldehyde.

Hope this helps,
John

John E. Simmons
Museologica
128 E. Burnside Street
Bellefonte, Pennsylvania 16823-2010
simmons.johne at gmail.com
303-681-5708
www.museologica.com
and
Adjunct Curator of Collections
Earth and Mineral Science Museum & Art Gallery
Penn State University
University Park, Pennsylvania
and
Lecturer in Art
Juniata College
Huntingdon, Pennsylvania

On Thu, Aug 11, 2011 at 10:52 AM, Frederick, Moretta RBCM:EX <
MFrederick at royalbcmuseum.bc.ca> wrote:

> Does anyone have experience with a glyoxal-based fixative called PREFER
> made by Anatech?  It has been suggested to us as an alternative to formalin
> fixation of fish.  I would be interested in hearing from anyone using this
> fixative with fish, invertebrates, and/or herps.****
>
> ** **
>
> http://www.anatechltdusa.com/productlit/preferlit.html****
>
> ** **
>
> Thanks, ****
>
> ** **
>
> Moretta****
>
> *
> ______________________________________________________________________________________________
> *****
>
> *Moretta Frederick *     Collections Manager, Invertebrates, Fish,
> Amphibians, Reptiles  |  Natural History
> [image: Description: https://sales.royalbcmuseum.bc.ca/logo.jpg]
> 675 Belleville Street, Victoria, BC Canada V8W 9W2
> T 250 387-2932
> MFrederick at royalbcmuseum.bc.ca   |   www.royalbcmuseum.bc.ca   |
> www.bcarchives.bc.ca ****
>
> Camp Inside Out is a week of behind-the-scenes and outdoor fun for kids age
> 8-10. July 11, 25 and Aug 8, 22.
> Check the What's On <http://royalbcmuseum.bc.ca/What_On/default.aspx>calendar. There’s always something happening!
> ****
>
> P Please consider the environment before printing this e-mail****
>



--
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.yale.edu/mailman/private/nhcoll-l/attachments/20110811/4a106474/attachment.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 2172 bytes
Desc: not available
Url : http://mailman.yale.edu/mailman/private/nhcoll-l/attachments/20110811/4a106474/attachment.jpe