[Histonet] Question about molecular sieves for EtOh

RCHIOVETTI <@t> aol.com RCHIOVETTI <@t> aol.com
Wed Aug 16 00:44:47 CDT 2006

In a message dated 8/15/2006 6:04:23 PM US Mountain Standard Time, 
lanbergld <@t> vcu.edu writes:

> Today I added 3A bead molecular sieves to my EtOh, so I can have
> (hopefully) a better tissue dehydration tomorrow. But the ethanol took on
> quite a murky appearance. It seemed that after a few hours it cleared, just
> a tiny bit. But it still looks kind of scary.
> Does this go away completely -- with longer sitting of the ethanol??? Or
> does anybody know a good way to separate, without the chance of humidity
> getting back into the EtOh?
> Thanks so much.


I've used 5A molecular sieve in ETOH for the same purpose, and I got exactly 
the same result: cloudy ETOH.

The cloudiness does go away after a couple of days and the sediment will 
collect on the bottom of the bottle.  I think it must be the result of small 
pieces of molecular sieve coming off the pellets.

I always played it safe...letting the ETOH stand for a couple of days, then 
carefully removing or decanting from the top to use it.

I also tried filtering the ETOH in a syringe with a luer-lok Millipore filter 
(0.4 micron pores, if I remember correctly) attached to the syringe, but 
honestly I could see no difference between decanting and filtering.  Both kinds of 
ETOH worked fine, and I never saw any kind of "crud" in my specimens.

I used the ETOH for electron microscopy specimen prep, so you'd think the 
precipitate would certainly be visible if it was present.  But I never had any 

I also used this technique to keep acetone anhydrous.  It worked like a 

Hope this helps.



Robert (Bob) Chiovetti, Ph.D.
The Microscope Works
Arizona's Microscopy Resource
132 North Elster Drive
Tucson, AZ 85710-3212 USA
Tel./Fax 520-546-4986
Manufacturers' Representative
Member, Arizona Small Business Association - ASBA

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