Column chromatography | Chemistry

Place a small piece of cotton wool at the bottom of the column to prevent solid material from entering the tap. Pour in approximately 1 cm depth of sand on top of the cotton wool, creating a level surface.

Mix the appropriate amount of silica with eluent (the solvent) in a beaker to form a slurry. Carefully pour the slurry into the column using a funnel, occasionally swirling the beaker to prevent silica from settling. Add more eluent as needed to maintain the slurry and assist with pouring.

Open the column tap to run eluent out until the liquid level reaches the top of the silica. Monitor the eluent level carefully and close the tap before the silica surface dries out completely.

Dissolve the crude compound in a small amount of eluent, ensuring complete dissolution. Use a glass pipette to add the solution evenly around the sides of the column.

Pour approximately 1 cm depth of sand on top of the column to protect the silica. Top up the column with eluent to prepare for fraction collection.

Open the tap at the bottom of the column to allow eluent to flow and collect fractions in test tubes or appropriate containers. Close the tap momentarily between fractions to switch collection vessels.

Continue collecting fractions while monitoring the movement of the compound down the silica column. Watch the eluent level and top it up as needed to maintain flow, continuing collection until the compound has fully eluted from the column.

Analyze the collected fractions to identify those containing the desired compound, using colour observation or TLC analysis if necessary. Remove solvent from the fractions using a rotary evaporator to isolate the purified compounds.