西亚试剂：：Ethanol Precipitation of DNA

Materials:

	3 M sodium acetate pH 5.2 or 5 M ammonium acetate
	DNA
	100% ethanol

1.  Measure the volume of the DNA sample.
2. 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.
3. Add 2 to 2.5 volumes of cold 100% ethanol (calculated after salt addition). Mix well.
4. Place on ice or at -20EC for >20 minutes.
5. Spin a maximum speed in a microfuge 10-15 min.
6. Carefully decant supernatant.
7. Add 1 ml 70% ethanol. Mix.
8. Spin briefly.
9. Carefully decant supernatant.
10. Air dry or briefly vacuum dry pellet.
11. Resuspend pellet in the appropriate volume of TE or water.