[Nhcoll-l] Answering a question about isopropanol storage
Sidlauskas, Brian
Brian.Sidlauskas at oregonstate.edu
Thu Jun 16 09:13:57 EDT 2016
Hi Everyone,
Thanks so much for your many responses to my post about isopropanol storage, and sorry for the delay in my response in kind. I’m at an (awesome) workshop on larval fish identification and curation at VIMS this week, and there hasn’t been much downtime. H.J. and John responded publicly, and I also received many private messages. All of the recommendations and information have been very useful, as is the literature trail. I’ve ordered a copy of John's book.
I’d like to echo H.J.’s point about working with local fire marshals. For better or worse, I’m stuck with using 50% isopropanol given that my local fire marshal has disallowed the use of 70% ethanol in large volumes. Transferring the whole Oregon collection into ethanol isn’t an option, nor is completely discontinuing the use of isopropanol for new specimens. The high quality of many of the specimens here, including those many decades old, suggests to me that even if this situation may not be ideal, is it unlikely to be disastrous.
I’ll be attending the one-day workshop on wet collections best practices at the end of the JMIH this year, and would be happy to volunteer to synthesize all the responses that I received as a starting point for a further conversation on this topic.
Thanks again!
— Brian
--
Brian Sidlauskas
Associate Professor and Curator of Fishes
Department of Fisheries and Wildlife
Oregon State University
104 Nash Hall
Corvallis, OR 97331
brian.sidlauskas at oregonstate.edu
541-737-6789 (office) 541-224-3850 (cell)
https://urldefense.proofpoint.com/v2/url?u=http-3A__ichthyology.oregonstate.edu&d=AwIF-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=IdKR33IJY8sIlwovLNO68LhHTQ3hjZ-ZMAyeNjDQrsM&s=Hqfyp29lKXwnlJtsdhzz2wq8j9dS3bBjvaVfX7U7XaA&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__Ichthyology.oregonstate.edu&d=AwIF-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=IdKR33IJY8sIlwovLNO68LhHTQ3hjZ-ZMAyeNjDQrsM&s=zxsm38woQHNPH0pstuuDZWgqKmh_e-Nbv3Ws-5n7NAo&e= >
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From: "H.J. Walker" <hjwalker at ucsd.edu<mailto:hjwalker at ucsd.edu>>
Date: Tuesday, June 14, 2016 at 4:40 PM
To: "nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>" <nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>>, Brian Sidlauskas <brian.sidlauskas at oregonstate.edu<mailto:brian.sidlauskas at oregonstate.edu>>, "simmons.johne at gmail.com<mailto:simmons.johne at gmail.com>" <simmons.johne at gmail.com<mailto:simmons.johne at gmail.com>>
Subject: Re: [Nhcoll-l] Answering a question about isopropanol storage
Hi Brian, John, et al.,
Disclaimer: I am one of the ichthyologists, mentioned by John, who believes that isopropanol (ISO) is essentially equal to ethanol (ETH) for long-term preservation of fish specimens. I have not seen John's book yet. By coincidence, I also authored a book published in 2014, with Phil Hastings and Grant Galland on fish diversity (Thank you for the kind review, Brian.), and in it are photos of hundreds of great looking (as you say below), ISO-preserved specimens from our Collection at SIO. John has used the phrase "in my opinion" and I echo those words here.
John and I agree that a collection in ISO should not necessarily be changed to ETH, but I have additional reasons.
1. Having endured many strict regs passed along by our vigilant Env, Health, and Safety Dept over the years, including a recent edict involving stricter safety procedures, including formaldehyde, we have received nothing restricting our use of ISO. I wonder if "twice as toxic" is as harsh as it sounds. John's sensitivity to ISO notwithstanding, we have had hundreds of researchers here over the years with only one headache to report, after the researcher had gone tank diving for hours. The headache ceased within a few minutes.
2. The Uniform Fire Code exemts 50% alcohol (ISO or ETH) solutions from those requirmeents for storing 70% alcohol solutions. Our fire marshal does not approve of specimen collections preserved in alcohol of any kind in concentrations higher than 50%, unless stored in flame-proof safety cabinets.
3. Thank you also, Brian, for sending a preview of your new article in Copeia which found no changes in morphometrics in specimens preserved in ISO. Thus the supposed "tissue matrix undergoes more breakdown" would seem negligible for our purposes.
4. Many of the other issues mentioned below, e.g., layering, more shrinkage, more loss of color (All colors except brown or black are lost, regardless of ISO or ETH.), etc., have been discounted in an article written by a number of colleagues and me with years of experience with ISO, in the ASIH Curation Newsletter series. I hope to get a copy to you soon.
5. The most important criterion for long-term preservation success is proper fixation in formalin, regardless of which alcohol is used subsequently.
6. I also have not seen "whether there’s actually good data suggesting that isopropanol storage is seriously problematic" and I look forward to seeing John's book.
Cheers,
H.J.
________________________________________
From: nhcoll-l-bounces at mailman.yale.edu<mailto:nhcoll-l-bounces at mailman.yale.edu> [nhcoll-l-bounces at mailman.yale.edu<mailto:nhcoll-l-bounces at mailman.yale.edu>] on behalf of John E Simmons [simmons.johne at gmail.com<mailto:simmons.johne at gmail.com>]
Sent: Sunday, June 12, 2016 7:09 PM
To: Sidlauskas, Brian
Cc: nhcoll-l at mailman.yale.edu<mailto:nhcoll-l at mailman.yale.edu>
Subject: Re: [Nhcoll-l] Answering a question about isopropanol storage
Brian,
This question comes up fairly regularly--often enough that I have saved the following response to the question of ethanol vs. isopropyl. Please feel free to ask if you have any further questions:
I get this question often. The short answer is, ethanol is a better long-term preservative than isopropyl because ethanol is less toxic (isopropyl is twice as toxic as ethanol, due to its faster permeation rate), ethanol causes less shrinkage of specimens, less fading of patterns and colors, and fewer user health issues (many people, myself included, get headaches from isopropyl fumes). However, this does not necessarily mean that a collection that is already in isopropyl should be changed to ethanol, as the change can create other issues.
Some people, particularly a few ichthyologists, insist that isopropyl is equal to or superior as a preservative, but in my opinion the information in the literature does not support their position. I have a full discussion of the pros and cons of isopropyl (with full references to the literature) in my book, Fluid Preservation: A Comprehensive Reference (2014). Here is a very brief summary: Isopropyl is a secondary alcohol, which means it dissolves lipids better than ethanol (lipid extraction is a problem with almost all preservatives, but is worse with isopropyl); as a secondary alcohol, isopropyl is more reactive with oxygen and forms ketones and unstable peroxides that can damage preserved specimens, which probably accounts for the greater loss of pigments. Isopropyl causes greater specimen shrinkage, can be difficult to mix thoroughly, may form concentration layers in tall containers, and has been reported to soften bone. One reason some ichthyologists prefer isopropyl is because specimens preserved in it are more flexible than those preserved in ethanol, however, the greater flexibility is because the tissue matrix undergoes more breakdown in isopropyl than in ethanol. But back to your question--should specimens in isopropyl be switched to ethanol? There is no clear and easy answer. Specimens in isopropyl have already undergone shrinkage, so switching to ethanol will not help that situation, although it may prevent a little long-term fading. From a human health perspective, ethanol is safer to work with, but there will be traces of isopropyl for decades to come in the ethanol after the switch. The change would be resource-consuming (time and money). Ideally, new specimens should be preserved in ethanol and the old ones left in isopropyl, but this would require some sort of container labeling so the two are not mixed up. So it all depends on what your priorities are.
The Canadian Museum of Nature is one of the few collections to report on what happens when specimens (fish, in this case) were initially preserved in ethanol, then switched to isopropyl, and then back to ethanol, so you might want to read their paper: Laframboise, S., R.M. Rankin, and M.M.L. Steigerwald. 1993. Managing change: alcohol transfer at the Canadian Museum of Nature. Pp. 28-33 in Snyder, A.M. (editor). The 1992 American Society of Ichthyologists and Herpetologists Workshop on Collections Care and Management Issues, 52 pp.
John E. Simmons
Museologica
128 E. Burnside Street
Bellefonte, Pennsylvania 16823-2010
simmons.johne at gmail.com<mailto:simmons.johne at gmail.com><mailto:simmons.johne at gmail.com><mailto:simmons.johne at gmail.com>
303-681-5708
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and
Adjunct Curator of Collections
Earth and Mineral Science Museum & Art Gallery
Penn State University
University Park, Pennsylvania
and
Instructor, Museum Studies
School of Library and Information Science
Kent State University
On Fri, Jun 10, 2016 at 2:04 PM, Sidlauskas, Brian <Brian.Sidlauskas at oregonstate.edu<mailto:Brian.Sidlauskas at oregonstate.edu><mailto:Brian.Sidlauskas at oregonstate.edu><mailto:Brian.Sidlauskas at oregonstate.edu>> wrote:
Hi folks,
Yesterday I received a private question about why the Oregon State Ichthyology Collection is mostly stored in 50% isopropanol rather than 70% ethanol. I get this question frequently, usually with some combination of dismay for the collection specimens and sympathy for me as their manager.
The basic answer involves historical contingency. I inherited a 20,000 lot cataloged collection in isopropanol (plus a lot more in backlog), and wasn’t about to change out 20,000+ liters of fluid. Nor do I have the funds to do.
The reasons that Carl Bond chose isopropanol in the first place (circa 1950) aren’t entirely clear to me, but my three best guesses are:
1) 50% isopropanol is slightly less flammable than 70% ethanol (slightly higher flashpoint, so perhaps better safety)
2) Isopropanol is (or was) less expensive, particularly because the stock solutions involve more water.
3) No one is tempted to drink the lab stocks of isopropanol
All that said, there’s definitely a sense that isopropyl alcohol is less than ideal for long term preservation. When I tried to follow that to a source a while back, I couldn’t find anything very detailed about what those drawbacks were.
I can certainly say that the specimens here at OSU generally look great. I’ve been posting photos recently on the collection’s Facebook page (https://urldefense.proofpoint.com/v2/url?u=https-3A__www.facebook.com_OregonIchthyologyCollection&d=AwIF-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=IdKR33IJY8sIlwovLNO68LhHTQ3hjZ-ZMAyeNjDQrsM&s=hehdhxGkeu0ium4RkUB8iOzN81oKQix67bZUxxAiGAA&e= )<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.facebook.com_OregonIchthyologyCollection-29&d=AwMGaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=dJo2jLcsWcYEYDAw5hIx5-keoCRISJ9nMwm_Xh3EQrU&s=0_88_eFhFM11IFP9_-xoVOwDi3EeEJC9ZaYLRDCBCbw&e=><https://urldefense.proofpoint.com/v2/url?u=https-3A__www.facebook.com_OregonIchthyologyCollection-29&d=AwMGaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=dJo2jLcsWcYEYDAw5hIx5-keoCRISJ9nMwm_Xh3EQrU&s=0_88_eFhFM11IFP9_-xoVOwDi3EeEJC9ZaYLRDCBCbw&e=> to help promote an online fish systematics course that I’m developing, if anyone want to take a look. There are also a bunch up at the collection’s database at https://urldefense.proofpoint.com/v2/url?u=http-3A__ichthyology.oregonstate.edu&d=AwIF-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=IdKR33IJY8sIlwovLNO68LhHTQ3hjZ-ZMAyeNjDQrsM&s=Hqfyp29lKXwnlJtsdhzz2wq8j9dS3bBjvaVfX7U7XaA&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__ichthyology.oregonstate.edu&d=AwMGaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=dJo2jLcsWcYEYDAw5hIx5-keoCRISJ9nMwm_Xh3EQrU&s=1f1Pyb1AX11PAF15Las-XYQW3LsZ-kTx8vZa4-C_aNs&e=><https://urldefense.proofpoint.com/v2/url?u=http-3A__ichthyology.oregonstate.edu&d=AwMGaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=dJo2jLcsWcYEYDAw5hIx5-keoCRISJ9nMwm_Xh3EQrU&s=1f1Pyb1AX11PAF15Las-XYQW3LsZ-kTx8vZa4-C_aNs&e=>.
And, we just published this paper suggesting that fish specimen shape is stable over decades of isopropanol storage.
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.bioone.org_doi_abs_10.1643_CG-2D15-2D303&d=AwIF-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=IdKR33IJY8sIlwovLNO68LhHTQ3hjZ-ZMAyeNjDQrsM&s=BUnloCAVK6gaddnD7Nsbrwdj2iVxXKbmyprOGQCApME&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__www.bioone.org_doi_abs_10.1643_CG-2D15-2D303&d=AwMGaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=dJo2jLcsWcYEYDAw5hIx5-keoCRISJ9nMwm_Xh3EQrU&s=0esFdfGbfJcHNMO0tSarf5Px7YjOIt7KtyHt-mwtym8&e=><https://urldefense.proofpoint.com/v2/url?u=http-3A__www.bioone.org_doi_abs_10.1643_CG-2D15-2D303&d=AwMGaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=dJo2jLcsWcYEYDAw5hIx5-keoCRISJ9nMwm_Xh3EQrU&s=0esFdfGbfJcHNMO0tSarf5Px7YjOIt7KtyHt-mwtym8&e=>
So, I’d be very interested to hear about whether there’s actually good data suggesting that isopropanol storage is seriously problematic.
Thanks for reading, and best fishes,
Brian
--
Brian Sidlauskas
Associate Professor and Curator of Fishes
Department of Fisheries and Wildlife
Oregon State University
104 Nash Hall
Corvallis, OR 97331
brian.sidlauskas at oregonstate.edu<mailto:brian.sidlauskas at oregonstate.edu><mailto:brian.sidlauskas at oregonstate.edu><mailto:brian.sidlauskas at oregonstate.edu>
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On 6/12/16 7:09 PM, John E Simmons wrote:
Brian,
This question comes up fairly regularly--often enough that I have saved the following response to the question of ethanol vs. isopropyl. Please feel free to ask if you have any further questions:
I get this question often. The short answer is, ethanol is a better long-term preservative than isopropyl because ethanol is less toxic (isopropyl is twice as toxic as ethanol, due to its faster permeation rate), ethanol causes less shrinkage of specimens, less fading of patterns and colors, and fewer user health issues (many people, myself included, get headaches from isopropyl fumes). However, this does not necessarily mean that a collection that is already in isopropyl should be changed to ethanol, as the change can create other issues.
Some people, particularly a few ichthyologists, insist that isopropyl is equal to or superior as a preservative, but in my opinion the information in the literature does not support their position. I have a full discussion of the pros and cons of isopropyl (with full references to the literature) in my book, Fluid Preservation: A Comprehensive Reference (2014). Here is a very brief summary: Isopropyl is a secondary alcohol, which means it dissolves lipids better than ethanol (lipid extraction is a problem with almost all preservatives, but is worse with isopropyl); as a secondary alcohol, isopropyl is more reactive with oxygen and forms ketones and unstable peroxides that can damage preserved specimens, which probably accounts for the greater loss of pigments. Isopropyl causes greater specimen shrinkage, can be difficult to mix thoroughly, may form concentration layers in tall containers, and has been reported to soften bone. One reason some ichthyologists prefer isopropyl is because specimens preserved in it are more flexible than those preserved in ethanol, however, the greater flexibility is because the tissue matrix undergoes more breakdown in isopropyl than in ethanol. But back to your question--should specimens in isopropyl be switched to ethanol? There is no clear and easy answer. Specimens in isopropyl have already undergone shrinkage, so switching to ethanol will not help that situation, although it may prevent a little long-term fading. From a human health perspective, ethanol is safer to work with, but there will be traces of isopropyl for decades to come in the ethanol after the switch. The change would be resource-consuming (time and money). Ideally, new specimens should be preserved in ethanol and the old ones left in isopropyl, but this would require some sort of container labeling so the two are not mixed up. So it all depends on what your priorities are.
The Canadian Museum of Nature is one of the few collections to report on what happens when specimens (fish, in this case) were initially preserved in ethanol, then switched to isopropyl, and then back to ethanol, so you might want to read their paper: Laframboise, S., R.M. Rankin, and M.M.L. Steigerwald. 1993. Managing change: alcohol transfer at the Canadian Museum of Nature. Pp. 28-33 in Snyder, A.M. (editor). The 1992 American Society of Ichthyologists and Herpetologists Workshop on Collections Care and Management Issues, 52 pp.
John E. Simmons
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On Fri, Jun 10, 2016 at 2:04 PM, Sidlauskas, Brian <<mailto:Brian.Sidlauskas at oregonstate.edu>Brian.Sidlauskas at oregonstate.edu<mailto:Brian.Sidlauskas at oregonstate.edu>> wrote:
Hi folks,
Yesterday I received a private question about why the Oregon State Ichthyology Collection is mostly stored in 50% isopropanol rather than 70% ethanol. I get this question frequently, usually with some combination of dismay for the collection specimens and sympathy for me as their manager.
The basic answer involves historical contingency. I inherited a 20,000 lot cataloged collection in isopropanol (plus a lot more in backlog), and wasn’t about to change out 20,000+ liters of fluid. Nor do I have the funds to do.
The reasons that Carl Bond chose isopropanol in the first place (circa 1950) aren’t entirely clear to me, but my three best guesses are:
1) 50% isopropanol is slightly less flammable than 70% ethanol (slightly higher flashpoint, so perhaps better safety)
2) Isopropanol is (or was) less expensive, particularly because the stock solutions involve more water.
3) No one is tempted to drink the lab stocks of isopropanol
All that said, there’s definitely a sense that isopropyl alcohol is less than ideal for long term preservation. When I tried to follow that to a source a while back, I couldn’t find anything very detailed about what those drawbacks were.
I can certainly say that the specimens here at OSU generally look great. I’ve been posting photos recently on the collection’s Facebook page (<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.facebook.com_OregonIchthyologyCollection-29&d=AwMGaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=dJo2jLcsWcYEYDAw5hIx5-keoCRISJ9nMwm_Xh3EQrU&s=0_88_eFhFM11IFP9_-xoVOwDi3EeEJC9ZaYLRDCBCbw&e=>https://urldefense.proofpoint.com/v2/url?u=https-3A__www.facebook.com_OregonIchthyologyCollection&d=AwIF-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=IdKR33IJY8sIlwovLNO68LhHTQ3hjZ-ZMAyeNjDQrsM&s=hehdhxGkeu0ium4RkUB8iOzN81oKQix67bZUxxAiGAA&e= ) to help promote an online fish systematics course that I’m developing, if anyone want to take a look. There are also a bunch up at the collection’s database at https://urldefense.proofpoint.com/v2/url?u=http-3A__ichthyology.oregonstate.edu&d=AwIF-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=IdKR33IJY8sIlwovLNO68LhHTQ3hjZ-ZMAyeNjDQrsM&s=Hqfyp29lKXwnlJtsdhzz2wq8j9dS3bBjvaVfX7U7XaA&e= <https://urldefense.proofpoint.com/v2/url?u=http-3A__ichthyology.oregonstate.edu&d=AwMGaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=dJo2jLcsWcYEYDAw5hIx5-keoCRISJ9nMwm_Xh3EQrU&s=1f1Pyb1AX11PAF15Las-XYQW3LsZ-kTx8vZa4-C_aNs&e=>.
And, we just published this paper suggesting that fish specimen shape is stable over decades of isopropanol storage.
<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.bioone.org_doi_abs_10.1643_CG-2D15-2D303&d=AwMGaQ&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=dJo2jLcsWcYEYDAw5hIx5-keoCRISJ9nMwm_Xh3EQrU&s=0esFdfGbfJcHNMO0tSarf5Px7YjOIt7KtyHt-mwtym8&e=>https://urldefense.proofpoint.com/v2/url?u=http-3A__www.bioone.org_doi_abs_10.1643_CG-2D15-2D303&d=AwIF-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=IdKR33IJY8sIlwovLNO68LhHTQ3hjZ-ZMAyeNjDQrsM&s=BUnloCAVK6gaddnD7Nsbrwdj2iVxXKbmyprOGQCApME&e=
So, I’d be very interested to hear about whether there’s actually good data suggesting that isopropanol storage is seriously problematic!
Thanks for reading, and best fishes,
Brian
--
Brian Sidlauskas
Associate Professor and Curator of Fishes
Department of Fisheries and Wildlife
Oregon State University
104 Nash Hall
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H.J. Walker, Jr.
Scripps Institution of Oceanography
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