Desalting with butanol precipitation

Hiranya S. Roychowdhury hroychow at
Fri May 19 14:45:33 EST 2000

Simplest way is to pprecipitate w/ EtOH (2- 2.5 vol) and then wash the ppt
w/ 66% EtOH. This will remove any salt that remains in the pellet.

sec-butanol (2-butanol) or n-butanol (1-butanol) is used to concentrate
nucleic acid solutions. When these are saturated w/ water, they help remove
certain organics (eg. EtBr, CHCl3, etc.). If used straight, these will
absorb the water from a nucleic acid solution and thereby concentrate it. Of
these two, sec-butanol does not absorb the salts while the n-butanol (being
slightly more polar) will absorb the salt along with the water. 

I think you can now decide how you may use the two different alcohols to
your advantage.

At 05:00 PM 5/19/00 +0200, Carmelo wrote:
>What I would like to do is to remove salts from a RNA solution eluted
>from a preparative gel. I don't want to use a G25 or a dialysis. 
>Some people use ethanol to precipitate the oligo and then wash it with
>ethanol 70%, some other use butanol.
>Hope I'm clear this time

Dr. Hiranya Sankar Roychowdhury
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at


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