[NHCOLL-L:4916] Re: Isopropanol as a preservative

[A.J.van_Dam at lumc.nl]

There are 3 main mechanisms of protein fixation.

 

*	Coagulation by dehydration (ethanol, acetone, ammoniumsulfate)
*	Denaturation by alteration of molecular structure (heat, detergents)
*	Polymerization by chemical (cross-)linking (formaldehyde)

 

Source: Walter Steinmann, 1972, Über die Konservierung in Flüssigkeit, Der Präparator 18:3-18

 

A fluid preservative does not have to have fixative properties (most alcohols do not, like glycols, glycerol, phenoxetol)

Most fixatives can also be used as preservatives but can be less suitable for long-term storage due to the forming of corrosive components by autoxidation and/or due to their mechanism of action (affecting DNA, color, structural integrity etc.). 

 

 

Andries J. van Dam, conservator

Museum of Anatomy
Leiden University Medical Center 
Postal zone T7-P
P.O. Box 9600 
2300 RC Leiden 
The Netherlands 
tel: +31 (0)71 526 9581
fax: +31 (0)71 526 8275 
E-mail: A.J.van_Dam at lumc.nl
Visiting address: Hippocratespad 21, building 3

 

Associate scientist, Natural History Museum, London
http://www.nhm.ac.uk <http://www.nhm.ac.uk/> 



Directory Board member ICOM-CC
http://www.icom-cc.org <http://www.icom-cc.org/>  

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http://www.alcomon.com <http://www.alcomon.com/>  



 

________________________________

From: owner-nhcoll-l at lists.yale.edu [mailto:owner-nhcoll-l at lists.yale.edu] On Behalf Of Richard Rosenblatt
Sent: maandag 2 augustus 2010 1:13
To: nhcoll-l at lists.yale.edu
Subject: [NHCOLL-L:4915] Re: Isopropanol as a preservative

 

I won't argue the point, but I know herps are placed directly into ethanol, as were fishes until the introduction of formalin in the early 20th century (?) Try that with isopropanol and you will soon have a pile of bones in the jar.

 

 

	Ethanol also lacks fixative properties!  It preserves mostly by dehydration.

	 

	
________________________________


	From: owner-nhcoll-l at lists.yale.edu [mailto:owner-nhcoll-l at lists.yale.edu] On Behalf Of Richard Rosenblatt
	Sent: Sunday, August 01, 2010 12:04 PM
	To: NHCOLL-L at lists.yale.edu
	Subject: [NHCOLL-L:4914] Re: Isopropanol as a preservative

	 

	Malcolm: Unlike ethanol, isopropanol is not a fixative. The fishes must have been fixed in formalin before being placed in iso.

	 

	 

	 
	
	

	The Arkansas State University Museum of Zoology has maintained fishes in isopropanol for decades.

		The hereptology specimens are kept in ethanol (after 24-48 hr fixing in formalin) for various reasons, but the fishes are housed in isopropanol

		and the preservation is pretty darn good.  I do not know if the fishes are formalin fixed first.

		 

		Malcolm

		On Sat, Jul 31, 2010 at 5:12 PM, Richard Rosenblatt <rrosenblatt at ucsd.edu> wrote:

		Amplifying HJ walkers brief comment, the Scripps Institution of Oceanography Marine Vertebrate Collection and  UCLA fish collections converted  to 50% Isopropanol in 1952. I came from UCLA and became curator in 1958 and continued the policy. The SIO collection now contains more than two million specimens, many of them delicate deep-sea fishes. We soon learned of the relative immiscibility of iso in water and the necessity to stir and bring preservative up to strength after washing out formalin. One advantage not often mentioned about iso is that when working with specimens it is not necessary to keep dipping them in water or spraying nearly as often as with alcohol specimens. When working with alcohol specimens you can see the scales curling and the fin-rays rapidly drying out under the microscope. I attribute this to the 50% water content as well as the lower vapor pressure of iso.
		Without belaboring the point, or entering controversies over possible chemical reactions, I can say that we have maintained our collection for more than 50 years in 50% isopropanol  with excellent results.

		
		
		
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