Column Chromatography Procedure
COLUMN CHROMATOGRAPHY GRADE SILICA GEL

1. Use a piece of wire to add a plug of cotton to the bottom of the column. There should be just enough cotton that the sand and silica will not fall out of the column.
2. Clamp the column to a ring stand and add enough sand to fill the curved portion of the column.  
3. Place a pinch clamp on the tubing, then fill the column 1/4 to 1/3 full with the initial eluent.  
4. Prepare a slurry of silica in the initial eluent by pouring dry silica into a beaker of eluent. (Add a volume of silica gel, such as 20 mL, to approximately double the volume of eluent, 40 mL.) CAUTION: keep the dry silica in your hood and be careful not to inhale the lightweight substance. A picture of packed column given below.
5. Quickly but carefully pour the slurry into the column. Stir and pour immediately to maximize the amount of silica that goes into the column instead of remaining behind in the beaker. You may find a clean spatula or glass rod helpful in transferring the silica.
6. Remove the pinch clamp to allow solvent to drip into a clean flask. Tap on the side of the column with a rubber stopper or tubing to help the silica settle uniformly.
7. Use a Pasteur pipet to rinse any silica that is sticking to the sides of the column. Allow the silica to settle while eluent continues to drip into the flask.
8. Once the silica has settled, carefully add sand to the top of the column. Sand is heavier than silica. If the silica has not settled, the sand may sink into the silica instead of forming a layer on top of it. (You may need to rinse down sand that sticks to the side of the column.