Separation of Photosynthetic Pigments by Thin-layer Chromatography

Make up a solvent consisting of 55% cyclohexane and 45% ethyl ethanoate. Place this to a depth of 0.5 cm in a tall beaker or chromatography jar, and cover the beaker to allow the air to become saturated with solvent vapour. Remove some leaves from a suitable plant, such as spinach, carrot or grass. Cut the leaves into small pieces and remove any stalks. Grind the leaves with a few cubic cm of propanone in a mortar to produce a concentrated green solution. Filter this solution to remove plant debris.

Take a ready-prepared strip of thin-layer chromatography sheet coated with silica gel. Mark a line in pencil 1.5 cm from one end of the strip. Using a fine glass tube or pipette, place a small drop of the chlorophyll extract in the middle of the pencil line. Allow this to dry and repeat the spotting several times, allowing to dry between each application, in order to get a concentrated spot of extract. This position is called the origin.

Place the strip in the beaker, leaning it against the side, making sure that the origin is above the level of the solvent. Cover and leave for 1-2 hours, until the solvent has travelled up the silica gel to a point near the end of the strip, making sure that the solvent does not run off the end. Remove the strip and mark this position. Allow the strip to dry.