[Nhcoll-l] Mixing EtOH

[Andrew Stewart]

Hi Tonya,

Yes, I used to have to decant and re-pour a dozen times to get the solution evenly mixed. Hardly ideal.

Now we decant 70% ethanol from two 50 litre carboys on a trolley. The alcohol is pumped in first, then the water added as the pressure seems to get it right to the bottom. Then the home-made tool (we call the ‘super swizzler’) is plunged up & down several times to ensure everything is thoroughly mixed. The ‘wings’ are made of plastic cut from n icecream container :), and flex to get past the narrow mouth. The concentration is then checked and so far it seems to work.

The larger black one for mixing alcohol in our 250 & 500 l tanks.

Sometimes a home-made solution works just fine.

Ngā mihi
Andrew Stewart

>><<<)o>
Assistant Curator NE (Fishes)
Museum of New Zealand
04 381 7314
027 7339363




From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Haff, Tonya (NCMI, Crace)
Sent: Wednesday, 7 September 2022 1:40 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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