Ethanol Precipitation of DNA
This procedure allows the concentration of DNA samples from dilute solution and the removal of unwanted 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 (normal microcentrifuge in cold room works fine). All centrifugations should be on "soft" (no brake) setting.
Procedure
- Transfer DNA to a container where it fills one fourth the total volume (a 500 µL tube should have no more than 125 µL of DNA solution, for example)
- Add one tenth volume of Sodium Acetate buffer to equalize ion concentrations
- Add at least two volumes of cold 100% ethanol; let stand in -20°C freezer for at least one hour
- Centrifuge sample for 15 minutes at highest speed in a 4°C microcentrifuge
- Remove as much supernatant as possible with a 1 mL micropipet; recentrifuge, then remove the rest with a 200 µL pipet
- Add 200 µL of cold 70% ethanol; centrifuge for 5 minutes in a 4 °C centrifuge
- Remove supernatant with a 200 µL pipet; evaporate remaining ethanol in a 37 °C water bath
- Resuspend pellet in desired volume of water or TE buffer
|
