Ammonium Acetate DNA Precipitation

This is a useful technique to purify DNA from enzymatic reactions.

– 10M stock of ammonium acetate (not been PHed)

1) Add 1 part ammonium acetate : 3 parts DNA solution to final concentration of 2.5M ammonium acetate

2) Add 2.5 final volumes of 100% ethanol (molecular biology grade)

3) Vortex to mix

• If the starting volume is >100ul, let the reaction sit on ice for 15 minutes. This gives a tighter pellet.

4) Spin for 15 min at max speed at 4C in a microcentrifuge. Orient the tube so that the hinge faces outwards.

5) Decant the liquid by carefully pipetting towards the side away from the hinge. The side away from the pelleted DNA.

6) Add 100ul of 70% ethanol ( molecular biology grade) to wash the pellet

7) Spin for 5 min at max speed at 4C in a microcentrifuge

8) Air dry  briefly until no ethanol can be smelled. However, do not over dry the pellet or it will never resuspend in solution.

9) Resuspend the DNA pellet in H20 or TE