1. Add an equal volume of TE (pH7.5-8.0) to phenol, mix well,
allow phases to separate.
2. Measure pH of the aqueous phase using a pH paper.
3. Remove and discard upper (aqueous) phase.
4. Repeat steps 1 to 3 until the pH of the aqueous phase is between 7.5-8.0.
5. Cover phenol with a layer of TE (pH7.5-8.0). Store protected from light at 4 degree.