# How do I refill an old biology specimen tube with preservative? **URL:** \ **Category:** Factual Questions\ **Created:** [July 30, 2014, 1:55am UTC](https://boards.straightdope.com/t/how-do-i-refill-an-old-biology-specimen-tube-with-preservative/694385 "2014-07-30T01:55:04Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![sengi](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@sengi](https://boards.straightdope.com/u/sengi)\ **Post date:** [July 30, 2014, 1:55am UTC](https://boards.straightdope.com/t/how-do-i-refill-an-old-biology-specimen-tube-with-preservative/694385/1 "2014-07-30T01:55:04Z")
I recently acquired a collection of old biology organism specimens in glass tubes from the 60s-80s, and in many of the tubes, the preservative has evaporated. Can I refill the tubes without damaging the specimens (i.e., will allowing new oxygen inside promote decomposition)? If so, should I use alcohol or formalin? I’m also planning to seal them with silicone glue afterwards and would appreciate knowing if there is any reason not to do so. Thank you! ---
**Author:** ![DocCathode](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doccathode/32/18773_2.png) [@DocCathode](https://boards.straightdope.com/u/DocCathode)\ **Post date:** [July 31, 2014, 6:43pm UTC](https://boards.straightdope.com/t/how-do-i-refill-an-old-biology-specimen-tube-with-preservative/694385/2 "2014-07-31T18:43:40Z")
I had a similar problem with the preservative evaporating in a specimen I received as a gift. I had the chance to ask the head curator of the Mutter Museum (which houses plenty of wet specimens, including the conjoined liver of Chang and Eng) what to do. She advised pouring out all the old liquid and soaking the specimen (in this case a bat) in distilled water. Then, put it in a solution of (let’s see if I can remember) of 9 parts distilled water and one part denatured alcohol. If I got any of this wrong, I’m sure a Doper with a degree in biology or chemistry will be along to correct me. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [July 31, 2014, 6:54pm UTC](https://boards.straightdope.com/t/how-do-i-refill-an-old-biology-specimen-tube-with-preservative/694385/3 "2014-07-31T18:54:35Z")
This is outside my area of expertise, but I can at least address this: > [@](#): > > (i.e., will allowing new oxygen inside promote decomposition) I would think that if the preservative has evaporated, the system is no longer air-tight, so oxygen is already in there. Opening it isn’t going to do any more damage, particularly if you immediately add new preservative. ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [July 31, 2014, 7:07pm UTC](https://boards.straightdope.com/t/how-do-i-refill-an-old-biology-specimen-tube-with-preservative/694385/4 "2014-07-31T19:07:40Z")
> [@sengi](#): > > I recently acquired a collection of old biology organism specimens in glass tubes from the 60s-80s, and in many of the tubes, the preservative has evaporated. Can I refill the tubes without damaging the specimens (i.e., will allowing new oxygen inside promote decomposition)? You’re probably fine. Unless the specimen is so fragile that decanting the existing fluid and replacing it with new fluid will damage it, which is a different problem. Oxygen won’t really do damage to the specimen for the short amount of time it’s exposed, and it should be totally immersed in your new preservative fluid, so it won’t have any parts exposed to the air. > [@](#): > > If so, should I use alcohol or formalin? Definitely use alcohol, not formalin. Formalin will eventually damage the specimen and should be used for fixing specimens and tissues, but not for long-term storage (they used to do storage in various concentrations of formaldehyde, but with the exceptions of larval tissues of fish, larval tissues of amphibians, & some invertebrates, formaldehyde tends to damage specimens - I think it may still be used for storing some human tissues as well - perhaps I should ask: what is the specimen of?) > [@](#): > > I’m also planning to seal them with silicone glue afterwards and would appreciate knowing if there is any reason not to do so. > > Thank you! For ease of access later on, I would seal with [Parafilm](http://www.amazon.com/Pechiney-Plastic-Packaging-Parafilm-feet/dp/B0017YDXFM) or saran wrap, that way if your alcohol evaporates again, or if there’s a crack in the glass, you can open it up easily. If you never intend to open it again, maybe silicon glue is a good substitute. ---
**Author:** ![sengi](https://avatars.discourse-cdn.com/v4/letter/s/b9bd4f/32.png) [@sengi](https://boards.straightdope.com/u/sengi)\ **Post date:** [August 3, 2014, 11:58pm UTC](https://boards.straightdope.com/t/how-do-i-refill-an-old-biology-specimen-tube-with-preservative/694385/5 "2014-08-03T23:58:38Z")
Thank you for the detailed response! The specimens are primarily amphibians and fish, but not larval. I read that I should use undenatured ethanol, 70% or higher or, as a less-preferable alternative, 50-60% undenatured isopropanol. Is it very important that the alcohol be undenatured? Is isopropanol much worse compared to high-proof ethanol? The reason I ask is that obtaining high-proof undenatured ethanol is difficult and expensive. Thank you again! ---
**Author:** ![wevets](https://avatars.discourse-cdn.com/v4/letter/w/e9a140/32.png) [@wevets](https://boards.straightdope.com/u/wevets)\ **Post date:** [August 4, 2014, 2:55pm UTC](https://boards.straightdope.com/t/how-do-i-refill-an-old-biology-specimen-tube-with-preservative/694385/6 "2014-08-04T14:55:20Z")
> [@sengi](#): > > Thank you for the detailed response! The specimens are primarily amphibians and fish, but not larval. I read that I should use undenatured ethanol, 70% or higher or, as a less-preferable alternative, 50-60% undenatured isopropanol. Is it very important that the alcohol be undenatured? Ugh! I would use denatured. My institution doesn’t even have a license to buy undenatured ethanol (it actually doesn’t turn out being much more expensive - there’s some available through Fisher from Decon Labs which I accidentally tried to order last week, to be promptly asked via email for our license.) 70% denatured ethanol will work fine. We’ve got hundreds, maybe thousands, of specimens in it. > [@](#): > > Is isopropanol much worse compared to high-proof ethanol? The reason I ask is that obtaining high-proof undenatured ethanol is difficult and expensive. Thank you again! I don’t know, because I have never used isopropanol for that purpose. I’ve received the impression that it is a second-best choice for long-term storage, probably from talking to others who wanted to preserve specimens, but I don’t know how the ‘second-best’ aspect manifests because I’ve never run out of 70% ethanol.