Phenol/chloroform extraction. 
Dilute your nucleic acid sample to 100–700 µL or divide your samples into tubes such that you have no more than 700 µL per tube.
Add an equal volume of phenol to the tube, vortex vigorously to mix the phases.
Spin in a microfuge at top speed for 1–2 min to separate the phases.
Remove the aqueous phase to a new tube, being careful not to transfer any of the protein at the phase interface.
Repeat the phenol extraction from step 4.
Repeat the phenol extraction from step 4.
Extract the sample with an equal volume of chloroform:isoamyl alcohol to remove any trace phenol.
Extract the sample again with an equal volume of chloroform:isoamyl alcohol to remove any trace phenol.
Precipitate the nucleic acid.
