[Nhcoll-l] [EXTERN] Re: Borax as a buffer for ethanol-preserved zoological specimens

[John E Simmons]

Although Berlin is fortunate to have very clean tap water, I do not advise
using it if you have deionized water available unless the pH of the
deionized water needs to be corrected. In addition to chlorine, tap water
usually contains other salts and minerals (otherwise it would not taste
pleasant) and often traces of heavy metals such as copper, lead, arsenic,
etc. from the water delivery infrastructure. It is important in
preservation of specimens to control all the variables and sources of
contamination that we can, and the use of deionized water is one method of
doing this. Any of the naturally occurring minerals, salts, or trace
chemicals may affect future research use of specimens.



If you do make the decision to add a buffer to the ethanol, be sure that
this information (particularly the date when this is initiated) is recorded
somewhere in a permanent record so future researchers will know. It is
often frustrating to diagnose problems with specimens because we do not
know how they were euthanized and preserved, so we owe it to future
researchers to record this information when we have it.



--John

John E. Simmons
US Fulbright Senior Scholar
Writer and Museum Consultant, Museologica
*and*
Research Associate, Earth and Mineral Sciences Museum & Art Gallery, Penn
State University
*and*
Investigador Asociado, Departamento de Ornitología, Museo de Historia
Natural, Universidad Nacional Mayor de San Marcos, Lima


On Thu, May 7, 2026 at 3:57 PM Dirk Neumann <d.neumann at leibniz-lib.de>
wrote:

> Chiming in; if you dilute the Ethanol yourself, use tab water; if I
> remember correctly, the Berlin tab water i´slightly chlorinated, you need
> to put a air bubbler in to drive the chlorine out. The Berlin tab water is
> slightly calciferous, that should do as a buffer for the pH. Do not use
> distilled water, because distilled water attracts carbon dioxide and builds
> up a bicarbonate buffer system which leans strongly to pH4.
>
> There is the very nice work of Marion Kotrba on the pH in Ethanol; her
> assessment showed nicely, that low pH concnetrations in crustaceans is not
> that much of an issue (the pH tends rather to be between 7-8.
>
>
> https://collection-forum.kglmeridian.com/view/journals/cofo/31/1-2/article-p84.xml
>
> Hope this helps
> Dirk
>
>
> Am 07.05.2026 um 19:06 schrieb John E Simmons:
>
> Before responding to your interesting question, we need a little more
> information.
>
> Why do you think your 75% ETOH might become acidic over time? The presence
> of the molluscan specimens alone provides a base (calcium) to buffer it.
> What is the source of acidification that you think you may have?
>
> What is the pH of the water you use to dilute your ETOH to 75%? Are you
> using tap water? Deionized water? Distilled?
>
> Borax is not a stable buffer over time--it works well initially, but over
> time may itself service as a source of acidification. I presume the
> molluscan specimens in fluid include tissues other than shells, in which
> case a preservative that is too basic will probably damage the
> proteinaceous parts of the specimen.
>
> How are the specimens treated before they are put into 75% ETOH? Do you
> use a fixative? If so, what is it?
>
> --John
>
> John E. Simmons
> US Fulbright Senior Scholar
> Writer and Museum Consultant, Museologica
> *and*
> Research Associate, Earth and Mineral Sciences Museum & Art Gallery, Penn
> State University
> *and*
> Investigador Asociado, Departamento de Ornitología, Museo de Historia
> Natural, Universidad Nacional Mayor de San Marcos, Lima
>
>
> On Thu, May 7, 2026 at 9:48 AM Katharina von Oheimb <
> katharina.von.oheimb at gmx.de> wrote:
>
>>
>> Hi everyone,
>>
>>
>>
>> At the Museum für Naturkunde Berlin, we use 75% denatured ethanol as the
>> standard preservative for fluid-preserved molluscan specimens. We are
>> currently evaluating the addition of borax (sodium tetraborate) as a
>> buffering agent, as it is practised in some other museum collections of
>> molluscs. The rationale is that unbuffered ethanol might become acidic over
>> time, potentially damaging the carbonate shells of molluscan specimens, in
>> particular the very thin and minute ones. I can imagine that this issue is
>> also relevant for ethanol-preserved samples of other animal groups with
>> calcium carbonate structures.
>>
>>
>>
>> I would be very interested to hear about your experiences with
>> borax-buffered ethanol for the long-term preservation of zoological
>> specimens. In particular, I would like to know:
>>
>>
>>
>> - What recipe do you use for mixing it?
>>
>> - Have you observed any effects on DNA quality?
>>
>> - Have you encountered any other undesirable effects, such as deposits on
>> specimens or other changes in specimen condition?
>>
>>
>>
>> Looking forward to hear from you!
>>
>>
>>
>> Katharina von Oheimb
>> **************************************
>> Dr. Katharina von Oheimb
>> Museum für Naturkunde
>> Leibniz Institute for Evolution and Biodiversity Science
>> Invalidenstraße 43
>> 10115 Berlin
>> Germany
>>
>> E-mail: katharina.von.oheimb at gmx.de
>> Website:
>> https://www.museumfuernaturkunde.berlin/en/the-museum/about-us/team/details/katharina-c-m-von-oheimb/
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>
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> --
>
> ******
>
>
>
> *Dirk Neumann*
>
> Collection Manager, Hamburg
>
>
>
> Postal address:
>
> *Museum of Nature Hamburg*
> Leibniz Institute for the Analysis
>
> of Biodiversity Change
>
> Dirk Neumann
>
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>
> 20146 Hamburg
> +49 40 238 317 – 628
>
> *d.neumann at leibniz-lib.de <d.neumann at leibniz-lib.de>*
>
> www.leibniz-lib.de
>
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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 H. Wappelhorst
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> _______________________________________________
> NHCOLL-L is brought to you by the Society for the Preservation of
> Natural History Collections (SPNHC), an international society whose
> mission is to improve the preservation, conservation and management of
> natural history collections to ensure their continuing value to
> society. See http://www.spnhc.org for membership information.
> Advertising on NH-COLL-L is inappropriate.
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