Photosynthesis Pigment Lab
Kerrie Johnson
LeMars Community HS
Objective:
Using paper chromatography, students will separate and observe the pigments that
give a leaves their color, determine the Rf value of each pigment, and learn their
function during photosynthesis.
Materials:
Poinsettia leaf
Spinach leaf
Evaporating dishes-2
Beakers-2, 250 ml
Chromatography paper
Acetone- 5ml
Procedure:
1. Use scissors to cut the bottom end of your chromatography paper to a
tapered end, as shown here:
2. Draw a faint pencil line a few millimeters above the pointed end of the
paper strip. Using the edge of a penny, crush the leaf into the paper over
your pencil line.
3. Pour about 5 ml of the acetone into your beaker (reaction chamber).
Straighten out your chromatography paper and set it into your beaker,
making sure that just a small portion of the tip is in the solvent.
*Make sure that the paper is NOT touching the side of the beaker and that
your pigment line is NOT sitting in the solvent.
4. Place the evaporating dish over the top of the beaker to stop evaporation of
the acetone.
5. Within a few minutes you may notice bands of different colors starting to
emerge: orange, yellow, light green, dark green, pink. Remove the paper
(chromatogram) from the beaker when the solvent has reached the top of the
beaker.
6. Mark the position of the solvent front and the center of each of the separated
pigments with a pencil. Then measure the distance of the solvent front from
the starting point and the distances traveled by the different pigments from
the starting point to the center of each band. Record your measurements in
the data table and make a sketch of your chromatogram for each plant.
7. Pick one of the leaves that you made a chromatogram of and calculate the Rf
values as a decimal fraction for each pigment and record your answers in the
data table.
Student Lab Report sheet for Photosynthesis Pigment Lab
Name _____________________________ Period ___________ Date ________
Results
Data Table
Analysis Questions:
1. Describe what happened to the original line of poinsettia pigment you put on
the chromatography paper.
2. Which of the two forms of chlorophyll is more soluble and how can you
tell?
3. List some other uses of chromatography.
4. Which of the pigments on the poinsettia pigment line migrated the farthest
and why?
5. Explain why leaves change colors in the fall.
6. What is the function of these plant pigments in photosynthesis?