Procedure

Preparation of the Column:

• Place the column in a ring stand in a vertical position.
• A plug of glass wool is pushed down to the bottom of the column.
• Prepare slurry of silica gel with a suitable solvent & pour gently into the column.
• Open the stopcock & allow some solvent to drain out. The layer of solvent should always cover the adsorbent; otherwise cracks will develop in the column.

Adding the Sample to the Column:

• Dissolve the sample mixture in a minimum amount of solvent (petroleum ether).
• Remove the solvent by placing the mixture in a rotary evaporator at a low temperature.
• Place the dry powder on a piece of weighing paper and transfer it to the top of the column through the funnel.

Developing the Chromatogram:

• Attach a dropping funnel filled with petroleum ether onto the column.
• Add petroleum ether continuously from the funnel to the top of the column.
• Open the stopcock carefully.
• The components of the mixture run down the column forming two separate yellow bands.

Recovering the Constituents:

• Continue running the petroleum ether till both the bands are eluted out separately.
• Collect the constituents in two different R.B flasks. (Ortho nitrophenol is obtained first, followed by para nitro phenol.)
• Evaporate the solvent by placing the mixture in a rotary evaporator.