LEAF CHROMATOGRAP

HYJIGYASA SHARMA

Introduction • Photosynthesis, is the process by which the plants

convert the light energy given by the sun to chemical food energy.• Brightly coloured pigments in leaves are essential to

the first steps of light absorption, with chlorophyll being the most important pigment.• There are two types of Chlorophyll- Chlorophyll A

which is bluish-green and Chlorophyll B which is yellowish green.

• During most of the growing season, leaves contain more chlorophyll than any other pigment, making them appear green. • In the fall, however, chlorophyll begins to break down,

and the other pigments, which have been there all along, are finally revealed: we see pretty yellow and orange fall leaves. • The yellow pigments in leaves are called xanthophylls,

and the orange pigments are called carotenoids.

CHROMATOGRAPHY• The process by which all the hidden pigments of a leaf

can be seen is called Leaf Chromatography.• Chromatography is the separation of a mixture by

passing it through a medium, through which different parts of the mixture will move at different rates.• Chromatography works because different substances

in a mixture have different degrees of solubility.

•Aim – To see the hidden pigments in a leaf.

•Materials -1. Soft green leaves (if no leaves are available, fresh spinach works fine, too)2. Scissors3. Mortar and pestle or food processor4. Glass or ceramic cup5. Isopropyl alcohol (or acetone in nail polish remover, but be careful—acetone -creates more fumes)6. Flat coffee filters7. Tape8. Pencil or straw

Activity

1. Use the scissors to cut up enough leaves to make a ¼ cup of pieces. Crush the leaves.

Procedure

2. Pour enough acetone over the leaves to cover them. Cover the cup and leave for 2 hours.

Procedure

3. Put the filter paper in the cup and leave for half an hour.

4. Different coloured bands should become evident along the strip.

Procedure

My Observations

After 1hr.After 2hr. Overnight.

• Your results may vary depending on the types of leaves that you chose and how careful your leaf chromatography technique was. You might also not see all the pigments.• An orange-coloured band is likely to be

near the top. Below that, you should see a yellowish band, a blue-green band, and a greenish-yellowish band, respectively.

Results

Leaf Pigments • A tree’s leaves are orange and yellow

even in summer. Most leaves include the pigments of all three colours• The pigment chlorophyll (the pigment

that makes the leaves green) is a much stronger pigment than the others. It covers the yellow (xanthophyll) and orange (carotene) pigments that are natural to a tree’s leaves. • But, come fall, a tree’s leaves produce

less chlorophyll.

Carotenoids •Xanthophylls- these are yellow coloured pigments that widely

occur in nature and make one of the two major divisions of the carotenoid group.

•

•Carotenes-these are the orange coloured pigments in the carotenoid group of plant pigments.

APPLICATIONS OF LEAF CHROMATOGRAPHY AND CHROMATOGRAPHY

■ Chromatography is a method for separating individual plant pigments. It is widely used in scientific research in bio technology area.

■ It is also used in food processing industry to separate out pigments. Pigments are used as natural food colouring agent and helps long life of the food product. The organic nature of plant pigments provides health benefits and nutritional advantage to diet

■ Chromatography plays a part in the realms of forensics, food regulation, athlete testing and even quality control in our favourite alcoholic drinks.

■ It is also used to separate any amount of quantities ranging from micrograms in laboratories to tons in chemical plants.

■ It is also used in removal of pesticides and insecticides like DDT in ground water with help of thin layer chromatograph

Bibliography• www.hometrainingtools.com• https://en.wikipedia.org• http://www5.bluevalleyk12.org/• www.education.com