[Nhcoll-l] Precipitate or Mold in Ethanol Stored Specimens

Thu Nov 29 05:16:19 EST 2018

Hi everybody,

It isn’t at all my field of competences, but I think, as most of us, that it may be formaldehyde.
I just wanted to say that I’ll finally be here for the meeting in Paris next week and I’m very excited about it, and about meeting all of you. As I am French and know well the place it will take place, don’t hesitate if you need some information or precision about Paris or/and technical questions.

See you soon,
Regards.

Juliette Galpin

De : Nhcoll-l [mailto:nhcoll-l-bounces at mailman.yale.edu] De la part de Bo Delling
Envoyé : mercredi 28 novembre 2018 17:20
À : neumann at snsb.de; nhcoll-l at mailman.yale.edu
Objet : Re: [Nhcoll-l] Precipitate or Mold in Ethanol Stored Specimens

Hi,

We have similar experience at NRM Stockholm, i.e. most certainly paraformaldehyde resulting from too short period in water prior to first EtOH step (20%). Our geologists did some analyses on the “white stuff” and found no mineral content such as CaCO3 or similar.

Bo Delling
Phd, Ichthyology
Collection Manager, Zoology

Swedish Museum of Natural History
Department of Zoology
Frescativägen 44
P.O. Box 50007
SE-104 05 Stockholm

Phone: +46 85195 4240

Från: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> För Dirk Neumann
Skickat: den 28 november 2018 11:27
Till: nhcoll-l at mailman.yale.edu
Ämne: Re: [Nhcoll-l] Precipitate or Mold in Ethanol Stored Specimens

Hi Alex,

we (John E. Simmons, Julian Carter and me - in preparation to attend a lecture in Paris next week :-) agree that it would be a good idea to pick one of those nodules and investigate the structure under a binocular; it should be easy to recognise any crystalline structure if there is any. If you see small white crystals (and your photos look very familiar to us), these would surely be a strong hint for paraformaldehyde, as Simon indicated. Colesterol is a rather a waxy substance, and you should be able to note the difference immediately.

Hope this helps,
with best wishes from us
(John, Julian an me, currently sticking or heads together and having much fun during our preparations for the Paris meeting next week)

Am 28.11.2018 um 00:20 schrieb Simon Moore:
Many thanks for this information - it is just what I am lecturing about in Paris next week to raise awareness of this type of problem!

I have often been asked to ID crystal growths and suspensions in fluid-preserved material and the answers (If there are any) are as varied as are the causes of their appearance.

Firstly I often dilute concentrated formalin to the standard 10% fixing strength using local tap water, this offers and usually maintains a neutral pH  (7.0 or just a bit below 6.5).  If tap water is used to dilute alcohols of any sort, to preservative strength (70% or 80%) then this produces a precipitate, usually with 24 hours of mixing.

Where fluids combine with animal and plant material during the fixation and preservation stages, they often leach solute by-products into the fluids.  Over years the fluid and specimen build to an equilibrium and assuming that no lipid leaching or similar contamination occurs (the cholesterol for example but isn’t this partly soluble in alcohol?), then this can go unnoticed until the jar is topped up with fresh preservative fluid and then a snow-dome effect can occur - looks terrible but the specimens are undamaged. Once the ’snow’ has settled and the fluid has cleared (or partially) one can see the effect (if any) this change may have brought about on the specimens but usually it’s slight or no change at all.

Crystals of calcium stearate have been analysed (by FTIR) adhered to specimens - how does that come about?  The causes and results can be quite bewildering but a record of treatment/s to specimens is most useful.

Mould (I’m a Brit!) will only start to appear if the concentration of alcohol falls below 30%, similarly it can grow in formalin at c. 2-3% concentration (0.8 - 1% formaldehyde) - these are the critical parameters for mould growth and (it appears) that only certain species of mould can grow in these conditions.

If anyone has any further thoughts I would be most interested (I only have a week!)  Or examples of weird looking contaminants attaching to fluid-preserved material please post these to me off-list but not too many!

With all good wishes, Simon.

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian,

[cid:C1E34A64-2782-4C13-9542-0187237C0047 at home]
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On 27 Nov 2018, at 19:23, Lazo-Wasem, Eric <eric.lazo-wasem at yale.edu<mailto:eric.lazo-wasem at yale.edu>> wrote:

Hi Alex,

This is what happens when a specimen fixed in formalin is not rinsed sufficiently in water before immersion in alcohol.  Depending on the size of the fixed specimen, one needs to wash the specimen for anywhere from a few minutes (small crustacea) to several days (large long fixed sponges, fish, etc.).  I’ve never tested like Judith Price mentions, but the person who hired me several decades ago cautioned me to rinse specimens in water before transferring to alcohol else I can expect precipitate.  It happened enough that I believe his cautionary note without understanding the chemistry.

Best, Eric

Eric A. Lazo-Wasem
Senior Collections Manager
Peabody Museum of Natural History
Yale University
170 Whitney Ave.
New Haven, CT 06520
203 432-3784<tel:203%20432-3784>

From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu<mailto:nhcoll-l-bounces at mailman.yale.edu>> On Behalf Of Alex Krohn
Sent: Tuesday, November 27, 2018 1:53 PM
To: nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>
Subject: [Nhcoll-l] Precipitate or Mold in Ethanol Stored Specimens

Hi everyone,

I recently found some bizzare white granules in some our ethanol preserved specimens. See the attached photos. The white granules tend to stick to the items in the jar, rather than rest at the bottom of the jar. They do not crush easily (like I imagine precipitates would), but instead squish more like tiny styrofoam bits or pieces (like I imagine mold would).

Has anyone seen this before? I washed the specimens and jars in fresh 70% EtOH, and then replaced the EtOH in the jar. So far no new granules have appeared. If anyone has any better ideas of what this might be or how to treat it, I'm very interested.

Thank you!

Alex Krohn

---------------------
Assistant Director
Kenneth S. Norris Center for Natural History
University of California, Santa Cruz

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