[Nhcoll-l] Is there a test to determine what fluid specimens are preserved in -- formalin or ethanol?

Fri Jan 4 02:03:29 EST 2013

Dear Rebecca,

completely agree with Charlie. As long as you don't have any climate 
control issues in your collection that could trigger mould issues, I 
would leave the dry specimens in the jar as they are. Especially in old 
historic specimens it is not always clear which type of preservation 
fluids were used for initial preparation/fixation. There is a whole 
variety of historic fixatives, some of them include heavy metal salts 
such as mercury in rather high concentrations (these were often used 
e.g. for preparations of marine invertebrates). If you don't know the 
history of preservation/fixation methods in your collection, I would be 
very careful in handling these specimens. Have in mind that prevailed 
usage of formaldehyde fixation/preservation starts roughly around 1910. 
Dried ethanol specimens may look rather poor (not initial fixation, only 
ethanol preservation = +/- dehydration of specimens to a certain 
extent). Be careful if your specimens have been prepared prior to 1900 
and still look +/- good or show some salty incrustations on the 
specimens, which could be an indicator for historic fixatives other then 
formaldehyde.

Rehydration will not restore the their original shape of specimens. If 
rehydration is necessary, I would also recommend method Simon Moore 
suggested in a previous NHCOLL-L posting (see below). For specific 
questions it might be worth contacting Simon directly.

All the best
Dirk

*************
From: Simon Morre, couteaufin at btinternet.com
Sent: 21/08/2011 12:00:02 GMT Daylight Time
Subj: Re: [NHCOLL-L:5600] FW: Rehydration of a sea anemone

Always rather ticklish when you have the holotype to perform such a 
radical treatment!
Bear in mind also that rehydration will improve the appearance and 
texture but it will compromise future DNA extraction/readings.  If you 
need further advice on this let me know.
I have also forwarded this to John Simmons who may also have some comments.
I tend to use Decon-90 at around 3 to 5% in deionised water as a 
rehydrating agent.
The reaction is catalysed by warming it to no more than 50 deg. 
Centigrade (hotplate) and make sure that the container has a loose lid 
to prevent massive evaporation during warming.
Obviously photograph and weigh the specimen prior to treatment.
Start the process first thing as it can take some time and so that you 
can monitor its progress during the day.
The fluid will start to yellow a bit and may smell rather fishy; the 
specimen will gradually sink into the fluid - this will only happen in 
an ideal situation, so if the specimen has expanded and feels soft and 
more flexible like it should if not dry, then it will have reached its 
'end-point'.  If it's still floating then it will have air trapped inside.
In which case.... place the specimen in clean water and place the 
container inside a vacuum desiccator.  Apply a mild vacuum to it and air 
should bubble out of the specimen.  After no more than a minute, stop 
the pump (making sure that the hose is removed from the desiccator and 
that the tap is closed *before* the pump is switched off - or it will 
suck the oil from the pump all over the specimen!!)
Then release the vacuum slowly and the anemone should sink completely or 
partly.  Repeat the process until no more air bubbles out.  Small 
amounts of trapped air will often slowly diffuse out later in the 
alcohol preservative (see below).
You should now have a fully rehydrated specimen.  Place into formalin to 
refix overnight and next day start to transfer into an alcohol 
dehydration ladder so that by the end of the day, the specimen is 
preserved in IMS once again.  Ensure that the jar seal is good!  
Finally, make a note of the treament for the specimen's record and 
reweigh the specimen, having drained off excess fluid and re-photo.
That should hopefully be it!
With all good wishes, Simon

Simon Moore MIScT, FLS, ACR,
Conservator of Natural Sciences,

Am 04.01.2013 05:34, schrieb CSTURMJR at pitt.edu:
> Rebecca,
>
> I will not opine on how to test what solution may have been used to store
> the specimens, however, I will question why you might want to rehydrate
> them. Unless there is a specific need to rehydrate a specimen, I would
> advocate to leave them in a dessicated state. The specimen is already
> dessicated and as such will probably stay that way for a long time (unless
> something is done to it). Rehydration methods can adversely affect a
> specimen. Better methods may be available in the future. Unless there is a
> need to rehydrate the specimen for a current study, store it dry. I have
> attached a chapter that I wrote six years ago and there are some
> references in Section 5.9 that you might like to read before rehydrating.
>
>
>> Hello all,
>>
>> We have several old collections in the park without any information about
>> how they were prepared.  Many need to be rehydrated and rehoused into
>> better storage.  Is there a simple test to determine what they are/were
>> preserved in before we rehydrate?
>>
>> thank you
>>
>> --
>>
>> Rebecca Cole-Will, Cultural Resources Program Manager  ~  Acadia National
>> Park, 20 McFarland Hill Drive, PO Box 177, Bar Harbor, ME  04609
>>   ~207.288.8728 ph., 207.288.8709 fx.
>> _______________________________________________
>> Nhcoll-l mailing list
>> Nhcoll-l at mailman.yale.edu
>> http://mailman.yale.edu/mailman/listinfo/nhcoll-l
>>
>
> Regards,
> Charlie
> .................................................
> Charlie Sturm
>
> Treasurer
> American Malacological Society
>
> Research Associate - Section of Mollusks
> Carnegie Museum of Natural History
> Pittsburgh, PA, USA
>
> Associate Professor - Family Medicine
> Fellow-American Academy of Family Practice
> Fellow-Academy of Wilderness Medicine
>
>
> _______________________________________________
> Nhcoll-l mailing list
> Nhcoll-l at mailman.yale.edu
> http://mailman.yale.edu/mailman/listinfo/nhcoll-l

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