Ethanol_precipitation

Precipitating out salts from DNA samples

Materials

• 3M Sodium Acetate buffer, pH 5.2 (store at 4°C)
• Cold 100% Ethanol (-20°C)
• Cold 70% Ethanol in sterile dH2O (-20°C)
• DNA sample
• 4°C Microcentrifuge (or normal microcentrifuge in cold room). All centrifuges should be on "soft" (no brake) setting.

Procedure

1. Transfer DNA to a container where it fills one fourth the total volume (a 500ul tube should have no more that 125ul of DNA solution, for example.
2. Add one tenth volume of Sodium Acetate buffer to equalize ion concentrations.
3. Add at least two volumes of cold 100% ethanol; let stand in -20°C freezer for at least one hour.
4. Remove as much supernatant as possible with a 1ml micropipet; reventrifuge, then remove the rest with a 200ul pipet.
5. Add 200i; of cold 70% ethanol; centrifuge for 5 minutes at 4°C.
6. Remove supernatant with a 200ul pipet; evaporate remaining ethanol in a 37°C water bath or heat block.
7. Resuspend pellet in 50ul of water or TE buffer.

-- LindseyWolf - 02 Dec 2011