[Nhcoll-l] Ethanol concentration for tissue samples

Wed Jan 27 16:06:50 EST 2016

Hi Sarah,

alcohol above 95% is technically dried (to remove the residual water 
which at this point can hardly be removed by distillation) with low 
boiling benzines. The resulting ethanol is traded as /High Gradient 
Grade/ ethanol or similar (99.9 %).

We had repeatly bad results using technically dried ethanol when 
preserving fish tissues (tissue : ethanol ratio was around 1:3 to avoid 
dilution from released tissue fluids). We do not know the exact reasons, 
but suppose residual chemicals used during technical drying or 
subsequent purification to have caused observed degradation of tissues.

Since then, we avoid 99.9 % and use 95% only, with good results. Tissues 
are stored at -25°C, however insects may be more stable under 
refrigerated conditions ( + 4°C), because released fats may form waxy 
deposits on the cuticula, which can hardly be removed if "empty" 
specimens (after extraction) should be prepared for final storage in dry 
collections.

Hope this helps
Dirk

(thanks for sharing the PDFs, Andy!)

Am 27.01.2016 um 18:56 schrieb Callomon,Paul:
>
> As Simon points out, it depends what you want the specimen for. On the 
> one hand, in our experience clean DNA (single genes or the whole 
> thing) can be got from specimens in concentrations as low as 70% 
> (though there is some variation between organisms); on the other, 95% 
> will shrink and harden a specimen, making it difficult to do 
> anatomical work without rehydration that itself damages cells. 
> Absolute alcohol (99.9%) has been denatured using chemicals, as 
> distillation only gets purity up to 95%. Any trace denaturant might 
> have unpredictable long-term effects on the specimen.
>
> PC
>
> *Paul Callomon*
> /Collection Manager, Malacology, Invertebrate Paleontology and General 
> Invertebrates/
>
> ------------------------------------------------------------------------
>
> *Academy of Natural Sciences of Drexel University, Philadelphia***
>
> 1900 Benjamin Franklin Parkway, Philadelphia PA 19103-1195, USA
> /callomon at ansp.org <mailto:callomon at ansp.org> Tel 215-405-5096 - Fax 
> 215-299-1170/
>
> *From:*nhcoll-l-bounces at mailman.yale.edu 
> [mailto:nhcoll-l-bounces at mailman.yale.edu] *On Behalf Of *Simon Moore
> *Sent:* Wednesday, January 27, 2016 12:47 PM
> *To:* Sarah K. Huber
> *Cc:* nhcoll-l at mailman.yale.edu; Eric Hilton
> *Subject:* Re: [Nhcoll-l] Ethanol concentration for tissue samples
>
> Hi Sarah,
>
> Presumably this relates to preservation of DNA?  If so, then it was 
> agreed, a few years ago, that using 96% ethanol and stored at 5 deg. C 
> was the best.  99% and absolute were found to be less effective.
>
> I am sure there will be other comments relating to this.
>
> With all good wishes, Simon.
>
> Simon Moore MIScT, RSci, FLS, ACR
> Conservator of Natural Sciences and Cutlery Historian,
> www.natural-history-conservation.com 
> <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.natural-2Dhistory-2Dconservation.com&d=AwMFAw&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=MdgXxloTDHBxPRNNRBDOtAs10obcg32_edRdQjHAD7U&s=rl1pZGY6sHOn5Tz9XTlu0JlqWEQ5y0JA4HMvMWtpVE0&e=> 
>
>
>
>
> On 27 Jan 2016, at 17:34, Sarah K. Huber <skhuber at vims.edu 
> <mailto:skhuber at vims.edu>> wrote:
>
>
>
> I recently had a graduate student request 100% absolute ethanol to use 
> for preserving tissue samples (fish muscle and/or fins). We routinely 
> use 95% ethanol (and all tissue samples are then stored in a -80 
> freezer); however, the student is adamant that 100% is the only 
> preservative that is acceptable for tissue preservation. Does anyone 
> have an opinion on 95% versus 100% ethanol for tissue preservation? 
> There is a very steep price difference between the two fluids, and my 
> understanding is that 95% ethanol preserves tissues just as well as 100%.
>
> Thanks,
>
> Sarah
>
>
> Sarah K. Huber, Ph.D.
> Curatorial Associate, VIMS Nunnally Ichthyology Collection
> Office 804.684.7104| Collection 804.684.7285
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