Re: Xylene BeadsX
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From: | "J. A. Kiernan" <jkiernan@julian.uwo.ca> |
To: | "Colbert, Laurie" <LColbert@phsca.org> |
Reply-To: | |
Content-Type: | TEXT/PLAIN; charset=US-ASCII |
On Tue, 23 May 2000, Colbert, Laurie wrote:
> I just read an article about using sodium aluminosilicate beads in xylene.
> These beads are supposed to remove water from the xylene so that you can use
> your xylene "indefinitely." These beads are listed as being available from
> Universal Oil Products in Des Plaines, IL. Has anyone ever tried these
> beads? Does anyone have phone number for this company? Thanks in advance.
You can buy granular material that absorbs water. It's called
_molecular sieves_ and your chemical catalogue should have
explanations about which type to use for various solvents. A
layer of molecular sieves in the bottom of a bottle of alcohol
or acetone can ensure that it's truly 100% anhydrous solvent.
BUT water and xylene don't mix. The water sinks to the bottom
as droplets. The only way you can get water invisibly in xylene
is if there's also quite a lot of alcohol present. Removing
water from an alcohol-xylene mixture would not leave you with
a liquid suitable for immersing slides in before coverslipping,
because alcohol does not mix with the usual resinous mounting
media.
Xylene collects two contaminants: alcohol during dehydration,
and dissolved wax during de-waxing of mounted paraffin sections.
Water isn't part of the picture. The story about removing water
with clay beads has to be something from a snake-oil salesman.
If there are molecular sieves that extract wax or alcohol from
xylene, these might be useful if they were extremely cheap. They
could never prolong the life of the solvent "indefinitely" because
molecular sieves cannot sequester immense volumes of the liquids
they preferentially absorb. It would almost certainly be more
economical to replace used xylene regularly, baeed on experience.
If you get through a lot, consider buying a still and recycling
it in the lab. Several HistoNet messages in the last 2 years have
encouraged redistilling xylene in big & busy labs.
John A. Kiernan,
Department of Anatomy & Cell Biology,
The University of Western Ontario,
LONDON, Canada N6A 5C1
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