Column Chromatography

Source: Lara Al Hariri at the University of Massachusetts Amherst, MA, USA

1. Preparation of the Dye SolutionExpand

   Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed.

   • Before you get started, put on a lab coat, safety glasses, and nitrile gloves, and make sure that the lab has a labeled organic waste container.
   • Prepare 5 mL of green food dye solution in ethanol. First, tare a clean empty 5-mL volumetric flask and slowly add 2.5 g of green food dye to the flask.
   • Add about 1.5 mL of 95% ethanol to the flask, stopper it, and seal it with plastic paraffin film.
   • Hold the stopper firmly in place and invert the flask several times to mix the ethanol and food dye together.
   • Then, add 95% ethanol to the fill line, reseal the flask, and invert it until the solution color appears even throughout.
   • Label the flask with its name and concentration and place it in a central area.
2. Preparation of the LaboratoryExpand
   • Ensure that the lab has labeled waste containers for silica gel and glass.
   • Fill a plastic wash bottle with acetone and set it by the organic waste container. This is for students or teaching assistants, who will clean the columns after the lab.
   • Place a container of silica gel powder, a container of sand, a box of laboratory wipes, several clean spatulas, and enough weighing boats for each student group by a calibrated balance in a well-ventilated area.
   • Place a bottle of 95% ethanol in a nearby hood. Then, make sure that the stopcocks for the columns fit securely but still turn easily.
   • Close the stopcocks after testing them and distribute the columns to the benchtop workspaces.
   • Make sure that each workspace has a lab stand or a scaffold and an appropriate clamp for the column being used.
   • Set out the following glassware and equipment at each student lab station (we suggest that students work in pairs):

     5    50-mL beakers

     1    100-mL beaker

     1    5- or 10-mL graduated cylinder

     2    50-mL graduated cylinders

     2    Small powder funnels

     1    Glass stirring rod

     1    Roll of laboratory tape

     1    Marking pen

     1    Ruler

     2    Pipette bulbs

   • Lastly, place glass or cotton wool, at least one long, blunt-ended metal or wooden rod, and a box of Pasteur pipettes in the central area with the dye solution.