Re: [Histonet] Question about molecular sieves for EtOh

From:Philip Oshel


Anhydrous copper sulfate works, but it has a 
worse dust problem than does molecular sieve. 
Also, molecular sieve can hold 3 to 4 times more 
water (on a weight basis) than can copper sulfate.
Copper sulfate is cheaper, but in the long run, I 
think sieve is cheaper. Buy 5 pound cans from 
e.g. Fisher.
Note: don't buy either of these with indicator! 
The indicator dye dissolves in the alcohol.
Both can be regenerated (dried) in a 200 deg C 
oven for 3 hours or so, then re-used.


>   If you want to have really anhydrous EtOH, why 
>don't you just add an excess of anhydrous copper 
>sulfate (white powder) that will absorb any 
>water in the EtOH?
>   I used this method for years and changed the 
>powder when it began to turn blue.
>   Copper sulfate anh. will not only dehydrate 
>the EtOH but will indicate you also when to 
>change it and probably will be cheaper that your 
>present method.
>   Hope this will help you!
>   René J.
>Lawrence D Lanberg/O/VCU  wrote:
>Dear Histonet Community,
>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.
>Larry Lanberg
Philip Oshel
Microscopy Facility Supervisor
Department of Biology
Central Michigan University
024C Brooks Hall
Mt. Pleasant, MI 48859
voice: (989) 774-3576
dept. fax: (989) 774-3462

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