EtOH ppt of DNA, what's wrong with this strategy?

Dr. Hiranya S. Roychowdhury hroychow at
Thu Sep 7 23:14:10 EST 2000

It most certainly will. Just make up a stock of 0.15M KOAc or NaOAC in
ethanol (or 0.2M in 2-propanol) for the precipitation.
The salt is not necessary if the DNA conc is very high. But usually it is
not and the ionic conc. has to be high enough for the NA's to ppt. That
seems to be about 0.3M for acetates and about 0.2M for chlorides.


At 01:46 PM 9/7/00 +0800, Peter O'Brien wrote:
>There's got to be a reason for adding  NaOAc to the aqueous DNA solution 
>BEFORE adding the EtOH.  Is this an absolute necessity?
>I'm doing >1000X precipitations/day of PCR products in 96 well plates, and
>am trying to save time, effort, and pipette tips in any way possible.  Will
>the ppt still work if I make a mix of the 95% EtOH and NaOAc then add it all
>at once?
>Any help greatly appreciated.  Please email as well as posting.
Dr. Hiranya Sankar Roychowdhury
Dept. of Molecular Biology	
PO Box 30001 - 3MLS
New Mexico State University
Las Cruces, NM 88003

Lab: (505) 646 4722
Office: (505) 646 8256
hroychow at


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