Ethanol Precipitation of DNA

Materials:

3 M sodium acetate pH 5.2 or 5 M ammonium acetate

DNA

100% ethanol

Measure the volume of the DNA sample.

Adjust the salt concentration by adding 1/10 volume of sodium acetate, pH 5.2, (final concentration of 0.3 M) or an equal volume of 5 M ammonium acetate (final concentration of 2.0-2.5 M). These amounts assume that the DNA is in TE only; if DNA is in a solution containing salt, adjust salt accordingly to achieve the correct final concentration. Mix well.

Add 2 to 2.5 volumes of cold 100% ethanol (calculated after salt addition). Mix well.

Place on ice or at -20EC for > 20 minutes.

Spin a maximum speed in a microfuge 10-15 min.

Carefully decant supernatant.

Add 1 ml 70% ethanol. Mix.

Spin briefly.

Carefully decant supernatant.

Air dry or briefly vacuum dry pellet.

Resuspend pellet in the appropriate volume of TE or water.