To ethanol precipitate nucleic acids, add salt, mix, add ethanol, mix, then freeze. Centrifuge to pellet the material.
Ammonium ions help keep free nucleotides in solution.
Mix well before freezing. The latter must be used for precipitating DNA in concentrated CsCl solutions since the CsCl salt will fall out of solution at lower temperatures. QS to 100 ml, filter sterilize with Nalgene 0.45 or 0.2 micron filter. Molecular Biology Protocols . Notes that appear below were taken from a discussion on this topic from one of the bionet newsgroups.