[Nhcoll-l] Mixing EtOH

[Joachim Händel]

Hello everyone,

I handle this similar to Simon: Only relatively small quantities - a
maximum of 7 liters at a time and rotate and swivel the canister several
times after mixing. I have not yet noticed any formation of layers.
I don't want to add air to the liquid - sorry Andy. Finally, we try very
hard to get air bubbles out of the mixture.


All the best
Joachim





--  
Joachim Haendel
                                                       
Center of Natural Sciences Collections
of the Martin Luther University
- Entomological Collection -

Domplatz 4
D-06099 Halle (Saale)
Germany

Phone:  +49 345 - 55 26 447
Fax:  +49 345 - 55 27 248

Email: joachim.haendel at zns.uni-halle.de




>>> Bentley, Andrew Charles 07.09.2022, 15:29 >>>

Hi Tonya




We usually bubble air through our alcohol while mixing which seems to do
a better job of mixing that simply rolling or inverting (although we
have never used a paddle).  We have not seen any later separation of the
fluid.  We use a hose off our lab air supply with a metal end that sinks
it down to the bottom of the fluid.  We usually let is bubble for a
couple of hours after filling the 25 liter carboy with 95% ethanol and
deionized water to dilute to 70%.




Andy

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Andy Bentley
Ichthyology Collection Manager
University of Kansas
Biodiversity Institute

Dyche Hall
1345 Jayhawk Boulevard
Lawrence, KS, 66045-7561
USA

Tel: (785) 864-3863
Fax: (785) 864-5335 
Email: abentley at ku.edu  

ORCID: https://orcid.org/0000-0002-3093-1258


http://ichthyology.biodiversity.ku.edu


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From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Haff,
Tonya (NCMI, Crace)
Sent: Tuesday, September 6, 2022 8:40 PM
To: nhcoll-l at mailman.yale.edu
Subject: [Nhcoll-l] Mixing EtOH




Hello all,

 

I have a question about mixing storage strength (70%) undenatured EtOH.
Typically we add the correct proportions of 95% EtOH and water to a
container and paddle or invert the container repeatedly to mix the
liquids, and allow it to sit for ~24+ hrs. The containers we like best
to use for dispensing 70% EtOH are 20L plastic water containers with a
tap at the bottom. Recently we used our digital alcohol meter to test
the alcohol concentration from the top and bottom (tap) of one of these
containers and found the alcohol concentrations wildly different  - ~80%
at the top and ~60% at the bottom – despite having been mixed more than
24 hours earlier. This makes me really concerned that we could be
regularly using concentrations that are much above 70% with specimens. I
wonder if any of you have had a similar problem, or if anyone can
suggest a solution? Is there a better way of mixing or of ensuring the
solution is properly combined? Any thoughts appreciated.

 

 

Thank you!

 

Cheers,

 

Tonya

-------------------------------------------------

Dr. Tonya M. Haff

Collection Manager

Australian National Wildlife Collection

CSIRO

+61(0)419569109

https://www.csiro.au/en/about/facilities-collections/collections/anwc


 
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