Leaf Pigment Chromatography

Our Biology I students just finished up a lab in which the leaf pigments are separated by paper chromatography.  It might seem like an odd time of year to be studying leaf pigments and photosynthesis, but our school runs a trimester system, and a student might be in any given semester of a class at an odd time of the year....... A discussion topic for another day!

As I am writing this, it has occurred to me that I have written on this topic before.  I just took a look back through all of my old blog posts, and I have indeed discussed this topic previously!  Now that I have re-read that old post, I am pretty pleased with how it turned out.  Check out this link to the previous post, and I will not cover the same content again:

Past Post on Paper Chromatography

Here are some new pictures that I took as my students were working on their lab.

Spinach leaves are placed in a mortar and pestle along with a little acetone.  Students grind the leaves until the acetone turns a dark green.  A small piece of capillary tubing is used to transfer drops of the pigment extract to a piece of chromatography paper.

When enough drops have been placed on the chromatography paper to make a dark green circle on the paper, it is ready to be placed into a large 25x200 test tube.

The large test tube has about 1/2 inch of petroleum ether in the bottom of the tube.  The pigments will immediately begin to separate.

Here is the finished chromatogram:

Here is the lab that I use with my students:

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