[Nhcoll-l] [EXTERN] Insights on Dealing with Pitric Acid

[Haff, Tonya (NCMI, Black Mountain)]

Hi Mackenzie,

We have had to deal with quite a few specimens that were preserved in Bouin’s solution (many older marsupial pouch young and the like). Some of them had crystalised picric acid around the neck or lid of the jar. When that happened and the jars had plastic ‘pop top’ lids, we submerged the entire jar under water for a few days, and then slowly opened the lids under water. As the risk is of friction and spark/heat, we deemed this very low risk. We then transferred to ethanol and Dirk’s suggestions there are excellent. We had a few jars that had metal lids, with dried picric acid around the rim. We chose to dispose of most of those (luckily very few and actually mostly not registered specimens), rather than have staff risk the potential friction of opening those jars.
I have always been very curious as to what the chances are of there being enough friction in the opening of a metal/glass jar lid to cause an explosion/reaction with picric acid – I know it’s scary stuff, but I’ve heard varying accounts in terms of museum jar lids. I’d be curious to hear if anyone else here knows more detail?

Cheers,

Tonya

------------------------------------------------------------------------
Dr Tonya Haff
Senior Collection Manager
Australian National Wildlife Collection
National Research Collections Australia, CSIRO
Canberra, ACT 2602 Australia
+61(0)419569109



From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Dirk Neumann
Sent: Wednesday, 5 March 2025 8:11 PM
To: nhcoll-l at mailman.yale.edu
Subject: Re: [Nhcoll-l] [EXTERN] Insights on Dealing with Pitric Acid

Hi Mackenzie,

besides the normal risk of specimens in Bouin/picric acid - which you surely are ware off, there is not so much different compared to other transfers from a water-based fixative into ethanol; except having a close look at the neck/lids of the jar to check for the formation of any (picric acid) crystals.

Because (usually small) specimens have been sitting in a quite acidic solution for long time, the tissues usually are weak when you start your transfer. This means, you probably should not leaven them for too long in water to remove most of the Bouin in a first step. Also, it might be worth considering smaller steps when ascending the alcohol ladder - again, depending on which specimens you move and how big they are.

Assuming that you are moving fish, and depending on how large they are, you can either do the normal 20/40/60/70, or, in smaller or more fragile specimens, you can gradually pull them up, i.e. adding 20% EtOH 5-6 times a day, then discard the 20% with the Bouin, replace with fresh 20%, continue to add 40% until you reach 40%, etc. This would be the preferred option for fish larvae, for example, where you want to avoid sudden osmotic changes and osmotic shock.

Hope this helps

Dirk


Am 04.03.2025 um 15:41 schrieb Mackenzie Helane Kinney:
Hello!

I am wondering if anyone has any experience and/or recommendations on how to transfer specimens out of pitric acid. Suggestions concerning both the preservation of the specimen as well as any safety precautions are welcomed!

Thanks in advance,
Mackenzie

Mackenzie Kinney, PhD
Collection Manager for Icthyology


[signatureImage]

Natural History Museum of Denmark
University of Copenhagen
Universitetsparken 15
2100 København Ø
Danmark




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Stiftung Leibniz-Institut zur Analyse des Biodiversitätswandels
Postanschrift: Adenauerallee 127, 53113 Bonn, Germany

Stiftung des öffentlichen Rechts;
Generaldirektion: Prof. Dr. Bernhard Misof (Generaldirektor), Adrian Grüter (Kaufm. Geschäftsführer)
Sitz der Stiftung: Adenauerallee 160 in Bonn
Vorsitzender des Stiftungsrates: Dr. Michael Wappelhorst
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