Concentration of Oligo DNA by Ethanol Precipitation Protocol Concentration of DNA by Ethanol Precipitation Protocol. Adapted fromBruce A. Roe, Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, Oklahoma. Usually 2.5 - 3 volumes of ethanol and/or acetate solution is added to the DNA in a microcentrifuge tube. This is then put into an ice-water bath for at least 10 minutes. The precipitation is performed by incubation at -20C overnight.