We are currently covering Photosynthesis in both topics 2 sl and 8 hl. In todays´class we carried out a what is known as a thin layer chromatography. The difference compared to the more common method of paper chromatography is the separating medium used for the solvent to travel through. In paper chromatography it is just a regular paper strip whereas in thin layer chromatography we used a plates made out of silica applied on a polyester backing. The advantage in this is that TLC is quicker in separating the components than PC.
In our chromatography experiment the purpose was to separate the pigments found in spinach leaves.
METHOD:
-Add a small spatula measure of anhydrous sodium sulphate (VI) to the bottom of a plastic Eppendorf tube. This is to remove any moisture that may be present. (Eppendorf tubes are commonly used for centrifugation).
-Place small pieces of a soft green leaf 8in this case spinach) in the bottom of the Eppendor tube. Add 5 drops of solvent A; consisting of 2 parts of ethyl ethanoate and 3 parts propanone.
-Press/stir the leaf with a metal probe to extract as much color as possible!
-Use a fine brush to place a small dot of colored solvent about 5mm from the bottom edge of the TLC plate. Mark this position. When dry put another dot again, repeat this until you have a small and concentrated dot.
-Using a pipette place 5ml of solvent B into a test tube.
-Place the plate into the tube.
-After a few minute remove the plate and mark the position of the solvent front once dried.
-Take a photo soon before the colored compounds detect light since they will fade.
In our chromatography experiment the purpose was to separate the pigments found in spinach leaves.
METHOD:
-Add a small spatula measure of anhydrous sodium sulphate (VI) to the bottom of a plastic Eppendorf tube. This is to remove any moisture that may be present. (Eppendorf tubes are commonly used for centrifugation).
-Place small pieces of a soft green leaf 8in this case spinach) in the bottom of the Eppendor tube. Add 5 drops of solvent A; consisting of 2 parts of ethyl ethanoate and 3 parts propanone.
-Press/stir the leaf with a metal probe to extract as much color as possible!
-Use a fine brush to place a small dot of colored solvent about 5mm from the bottom edge of the TLC plate. Mark this position. When dry put another dot again, repeat this until you have a small and concentrated dot.
-Using a pipette place 5ml of solvent B into a test tube.
-Place the plate into the tube.
-After a few minute remove the plate and mark the position of the solvent front once dried.
-Take a photo soon before the colored compounds detect light since they will fade.
In the second image we can clearly see how the different pigments in the chlorophyl of the spinach have been carried along by the solvent on the TLC paper. We can assume that these lines indicate the presence of certain pigments such as chlorophyll a and b, lutein, ß-carotene and other xanthophylls. Chromatography works due to the different masses of different molecules and substances. Heavier molecules will only be moved a little bit whereas light molecules will be moved further away from the starting point. Chromatography is a method used to identify the components of a substance and is often used in criminology.