Leaf Chromatography

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★☆ Some safety precautions required to perform safely

Categories: Separating Mixtures, Plants, Respiration and Photosynthesis

Alternative titles: Separating Plant Pigments

Summary

Chromatography is used to separate pigments in green leaves. By dissolving leaf pigments in alcohol and drawing them up filter paper, students can see hidden colors like carotenoids and anthocyanins that are usually masked by chlorophyll.

Procedure

Collect green leaves from several tree species, keeping each type separate.
Tear leaves into pieces and place them in a beaker or glass jar.
Add enough isopropyl alcohol to cover the leaf pieces, then seal the container with plastic wrap to reduce evaporation.
Place the beaker in a dish of hot tap water for about 30 minutes until the alcohol turns green.
Cut a strip of filter paper (or coffee filter) and tape it to a pencil. Suspend the pencil across the beaker so the strip just touches the pigment-alcohol mixture.
Allow the liquid to travel up the paper for 30–90 minutes. Observe the separation of colors as different pigments move at different rates.
Compare pigment variety among different tree species.

Links

Leaf Chromatography Activity - Students - Nature School:

Leaf Chromatography - Kids Fun Science:

📄 Leaf Chromatography Experiment - Home Science Tools: https://learning-center.homesciencetools.com/article/leaf-chromatography-science-project/

Variations

Try leaves collected at different times of the year (spring vs. autumn).
Test whether boiling water baths or longer soaking times release pigments more effectively.
Compare pigment separation using different solvents (e.g., acetone, ethanol).

Safety Precautions

Adult supervision recommended.
Handle rubbing alcohol with care; keep away from flames and avoid ingestion.
Work in a well-ventilated space.
Wash hands after handling leaves and chemicals.

Questions to Consider

Why do leaves appear mostly green in the summer? (Chlorophyll masks other pigments during photosynthesis.)
What pigments become visible when chlorophyll breaks down in the fall? (Carotenoids—yellow/orange; anthocyanins—red.)
Why do pigments travel at different speeds on chromatography paper? (Differences in solubility and interaction with the paper.)
Which tree leaves showed the most pigment variety, and what might that predict about their fall color? (Leaves with more pigment diversity will likely show brighter fall colors.)