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Re: WSN: salting out, deionized H2O,.. (fwd)
Sender: kelias@LLC.org (Robert Keith Elias)
Subject: Re: WSN: salting out, deionized H2O,..
Dear Mr. Walker;
I am not a chemist and I know nothing about organic chemistry,
but I do have practical experience in water treatment.
> Please excuse me if my query is inappropriate - but museum
> conservation science is a relatively new field and relevant
> information sources are scarce. In the treatment of objects
> in our care, we are not always certain whether we are
> arresting degradation or sometimes promoting it.
> The question of salting out refers to proteins that are in
> solution. My question concerns the forces that would
> solubilize amino acids and peptides out of native proteins.
I too was puzzled by the discussion of "salting out" (colloids)
which followed your question.
> If I immerse keratin fibers in water of low ionic strength, I
> do not want components of the fiber to go into solution. Is
> this a possibility which increases as water becomes
> increasingly pure?
In my opinion, there is a very great risk of damaging fibers
that are immersed in deionized water. Deionized water is
extremely aggressive, and will dissolve almost anything.
> My supplier says that a copper penny will dissolve in ultra
> pure water. In industrial wet treatments of fibers,
> protective colloids are utilized to counteract certain
> reactions in aqueous media. Is there, then, a characteristic
> of deionized water that could solubilize ionizable components
> of a protein fiber?
DEFINITELY yes. Ionizable components are those that are most
likely to go into solution, owing to the polar nature of water.
I do not KNOW what you should be adding to the water, but it
would make sense (to me) to completely saturate the deionized
water with compounds that are of the same type as those found in
the fibers you want to protect. That way the fiber and the
dissolved compounds would be in equilibrium, and thus the
tendency for the fiber to dissolve would be removed.
A simple and stupid way that MIGHT achieve this would be to
boil cloth identical to that you want to protect in deionized
water, and then filter off the particulate matter that remains.
(If you don't have any such samples then you might use a mix of
fingernails, hair, feathers etc as alternative keratin fibers -
but I REALLY do NOT know what I am talking about here.)
> Your help is greatly appreciated.
I hope I have been of help.
Cordially;
Robert Keith Elias
Internet: kelias@LLC.ORG