Open the stopcock at the bottom. If it does not leave fast enough, liquid will start to leak out where the top syringe is attached to the column. Sodium azide is poisonous. Wear gloves and goggles. Wash your hands well after using the sodium azide solution as well as the gel which is stored in a sodium azide solution.
Sodium azide reacts with copper, lead, and acids to create dangerous products.
Keep it away from these materials. Let buffer run through the column for about 15 minutes. Shut the stopcock and leave about 2 cm of the liquid on top of the column. Remove the syringes from the top and bottom of the column putting the yellow plastic caps that came with the column in their place. During storage, make sure that there is always a little bit of liquid above the beads in the column.