SMP ELYON CHRISTIAN SECONDARY SCHOOL
CLASSWORK
ACADEMIC YEAR 2022/2023
Student’s Name :
Day / Date :
Chlorophyll extraction by chromatography
During this experiemnt we will extract, separate by paper chromatography,
and compare different plants pigments found in two different leaves.
These are the 4 types of pigments that we may find out:
● Chlorophyll A - Dark green
● Chlorophyll B - Yellowish-green
● Xanthophylls - Yellow
● Carotenoids - Orange
(plants aren’t limited to these pigments)
Step 1. Write down a function of these pigments in plants
Plant pigments have a crucial role in regulating photosynthesis, growth, and
development.
To attract insects, birds, and other animals for pollination and seed
dissemination, pigments function as visible signals. Moreover, pigments shield
plants from the harm that UV and visible light can do. One of the pigments
found in plants, chlorophyll, is also used to produce glucose, which serves as
the plant's food. we are only talking about pigments involved in
photosynthesis. You should describe the respective function of the pigments
mentioned above.
Step 2. Extraction
Describe how to extract plant pigments from the chloroplast
Solvent, microwave, ultrasound, pressured liquid, pulsed electric field,
supercritical fluid, enzymes, and extraction techniques employing green
chemistry are some of the frequently used techniques for pigment extraction.
describe what we have done to extract the pigments out of the plant
What is the use of acetone?
Acetone produces a higher chlorophyll content than the other solvents,
making it the most effective solvent for chlorophyll extraction.
What is the benefit of adding sand while grinding the leaves?
Before grinding, the sample is covered in sand to weaken the sample's highly
stiff plant cell walls. The cell walls are successfully destroyed by the
mechanical pressure applied by the granular sand, which also makes it
possible to remove the pigments with ease.
Step 3. Centrifugation
Explain how centrifugation can separate various substances
Using the sedimentation principle, a centrifuge operates as a result of
gravitational force (g-force), objects separate based on their densities.
Take a picture of the centrifuge tube after centrifugation and label the
different phases
Step 4. Paper chromatography
Explain how paper chromatography can separate the different pigments
The dissolved pigments are carried up the paper by the solvent as it moves.
Because the pigments are not all equally soluble, they are transported at
varying speeds. The greatest distance will be covered by the most soluble
pigment, while the shortest distance will be covered by the least soluble
pigment.
Define the retention factor Rf
The ratio of the solute's and solvent's travel distances is known as the Rf
(retardation factor).
Take a picture of the result of the chromatogram
Calculate the Rf values for the different pigments and arrange them into the
result table
Name of the pigment Theoretical Rf value Observed Rf value
(cm) (cm)
Carotene 0.98 cm 0.3 cm
Chlorophyll A 0.59 cm 0.2 cm
Chlorophyll B 0.49 cm 0.2 cm
Pheophytin 0.59 cm 0.1 cm
Xanthophyll 1 0.15 - 0.35cm 0.1 cm
Xanthophyll 2 0.15 - 0.35cm 0.2 cm
Anthocyanins 0.32 - 0.62 cm 0.1 cm
Which pigment has the highest solubility? Carotene.
Use the table below for the theoretical Rf value
Write a conclusion about the experiment
Chromatography is the process of separating substances by having the
pigments get carried upwards on paper chromatography. Because the
pigments are not all equally soluble, they are transported at varying speeds.
When they have different solubilities, the Rf values are different, the higher
the value, the more soluble it is.
Suggest how to improve this experiment
Resolution in thin-layer chromatography (TLC) can be improved by reducing
the size of the sample spot and increasing the separation between the
developed spots. The Rf value is affected by the interactions of the various
components as well as the concentration of the component in the sample,
so the concentration could have been the cause to the drastic difference
between the theoretical and actual results.
