Using reverse-phase liquid chromatography and spectrophotometric detection, the
extracted pigments from spinach will be separated and analyzed.
Students will learn about plant
pigments, how to extract pigments from plant cells, to use liquid chromatography to separate
complex mixtures, and to determine efficiency using selectivity and resolution.
There are three families of plain pigments: porphyrins, carotenoids, and flavenoids.
porphyrins consist of the chlorophylls a and b.
These pigments are usually in green plants and
are involved in photosynthesis.
However, when sunlight decreases, the production of
chlorophyll decreases also.
As a result, leaves change colors in the fall.
pigments in fall leaves are carotenoids.
This family has two subgroups: carotenes (orange-
yellow and red pigments) and xanthophylls (yellow).
Like the porphyrins, this family is also
involved in photosynthesis to a smaller degree.
However, the amount of carotenoids in plant
cells remains fairly constant year round.
The last family is the flavonoids, which have three
classes: flavones, flavonol, and anthocyanin.
Most flavonoids contribute to the pigments in
flowering plants, although there are some flavonoids in leaves.
Anthocyanin, which reflects red,
blue, and purple colors, has a glucose group, and its production is dependent on carbohydrate
availability, sunlight, and temperature.
Also, it has the ability to change color according to the
Anthocyanin is red in the most acidic conditions, and as the medium gets more basic, it
turns to purple and then blue.
It is also responsible for leaf coloration in the fall.
There are several ways to extract pigments from plant cells.
A mortar and pestle, along
with sand, can be used.
Also, a blender and acetone can be used to break up the plant cells, and
this becomes an organic solution.
Then, the same volume of saturated salt solution would be
added to the organic solution, creating two layers.
The aqueous layer will contain most of the