Another consideration is what you want to be able to get from the soft
parts. If you are interested in DNA, higher concentrations of ethanol
are best. Again, changing the ethanol a few times fairly soon after
collecting helps ensure that there is not too much water and other
stuff derived from the animal in the ethanol. Isopropanol doesn't
work well for DNA; ethylene glycol tends to take up water readily and
so is not so good (the water generally contributes to breakdown of DNA
as well as allowing hydrogen ions to form and react with the shell).
On Wed, Mar 13, 2013 at 5:39 AM, jan steger <[log in to unmask]> wrote:
> Dear Conchlers,
>
> I recently came across some self-collected land-snails which had been stored
> in high-percentage (96%) denatured ethanol for some years (the "oldest"
> samples were collected in 2007) and noticed that some of them, especially
> the fragile or glossy species (e. g. Vitrinidae, Zonitidae) had become dull
> and formerly transparent shells white.
> The alterations look to me like the beginning of shell corrosion, although
> non of the specimes has shown signs of dissolution yet.
>
> I dried many of these sample, but I have some marine specimens much more
> valuable to me preserved in pure, non-denatured ethanol (again, a
> concentration of around 96%) and am not sure what to do in order to preserve
> the shell as well as the tissue for long time.
>
> On the internet and in the great publications by Daniel Geiger (incl. the
> new monograph about Scissurellidae) I found, that corrosion of calcareous
> shells is a general problem with ethanol (especially with small species) as
> acidic substances from the tissue might leach into the alcohol and damage
> the shells.
> There was also information that buffers like powdered calcite, aragonite or
> borax could be added to the ethanol to keep pH constant within narrow
> ranges, but that recristallization migh occur, which also damages the shell.
>
> Now I donīt know what to do, as I would prefer to keep my alcohol-collection
> for the next decades (Iīm an only 22 years old zoology-student in Vienna,
> Austria) without destruction of the shells, if this is possible.
>
> Does anyone of you have experience in long-term storage of thin-shelled
> mollusc-specimens or similar experiences?
> What concentration of ethanol is the best for storing shell-bearing
> molluscs? How do you store your wet specimens?
> Has anyone used buffers for alcohol-specimens, and if, which are suited best
> according to your experience?
> How can corrosion be avoided?
>
> Thank you very much in advance! Any help would be greatly apreciated!
>
> best regards,
> Jan
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Dr. David Campbell
Assistant Professor, Geology
Department of Natural Sciences
Gardner-Webb University
Boiling Springs NC 28017
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