ethanol precipitation

[Bill Melchior, NCTR/FDA]

>The problem I have with the use of ammonium acetate is the
>requirement for the addition of two volumes of salt in addition to
>the ethanol.  This usually screws up the maximum volume that I can
>handle in a 1.5 ml tube.  Any suggestions for avoiding this, like
>using higher concentration of amm. acetate?

This can be a problem.  My procedure is to add 1/2 volume of 7.5 M
AmOAc, followed by twice the NEW volume of EtOH, giving a final volume
4 1/2 times as great as that of the original DNA solution.  If anyone has
had experience using an even higher salt concentration, I too would like 
to hear it.
________________________________________________________________________________
The opinions stated are mine, not those of NCTR or its sponsoring organizations.

Bill Melchior                                ||   "You have lawyers the way
National Center for Toxicological Research   ||    other people have mice."
Jefferson, AR  72079                         ||
(501) 543-7206                               ||   -Kenneth Duncan, English
                                             ||    Health & Safety Executive,
WMELCHIOR at NTDOC.NCTR.FDA.GOV                 ||    to US regulators