Ethanol precipitation - can't get rid of all the EtOH! (Aug/19/2005 )

Hi!

I seem to fail with my EtOH precipitation over and over... Or at least I seem to be needing much more time (over night!) to get rid of the alcohol from the tubes. What am I doing wrong?

When I empty the tubes I don't use a pipett, but turn the tubes upsidedown and put the on a towel to 'pull out' the last visible drops of EtOH.

Hi!
That used to happen to me too. You let your samples to dry and you steel find some liquid in the bottom of your sample tube, right? Well, I read somewhere that the ethanol evaporates and the liquid that stays in the tube is water that evaporates slower than the alcohol. I usually hidrate my samples after 15-30 minutes, because if they dry too much it will be harder to elute them properly. Hope it helps!

Hi I generally after decating keep the tubes on dry waterbath set at 38-40C for say some 10min.

h
after first centrif,^pipet as much as you can, re spin briefl (at least 2OOO rpm) and discard the residual ethanol. Let sit on bench or at 37° for 10 to 30' and you would have got rid of ethanol.
fred

I remember hearing this trick before. Do an additional wash with pure EtOH at the end to remove residual water. This will dry out a lot quicker. I'm not sure if this is good for the DNA though.