Principle of Paper Chromatography

Principle of paper chromatography

PRINCIPLE: The principle involved in separation by paper chromatogr ch romatography aphy is largely by partition coefficient phenomenon. Separation of components depends on both their solubility in the mobile phase and their differential affinity to the mobile phase and stationary phase.

Emphasize on the role of pigments in

plants

Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light. and transfer that light energy by resonance energy transfer to a specific chlorophyll pair in the reaction center of the photosystems.

They are responsible for the orange colour of many fruits and vegetables. They also protect plant tissues by helping to absorb the energy from singlet oxygen, an excited form of the oxygen molecule O 2 which is formed during photosynthesis. Carotenes are accessory, orange coloured light-harvesting pigments in photosynthesis Beta-carotene is a precursor to vitamin A in animals Carotenes serve as antioxidants The color of carotene plays a role in reproduction Xanthophyll is an accessory pigment in plants.  Accessory pigments absorb additional portions of the light spectrum which increases the light  energy available for photosynthesis.

How many types of

pigments are there in plants and give their importance?

There are four different pigment groups present in leaves of photosynthesizing plants. Chlorophyll a Chlorophyll b Carotenoids  xanthophylls carotenes

Define Rf

value

It is defined as the ratio of the distance travelled by the solute to the distance travelled by the solvent front

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How

many types of filter papers are available for chromatographic techniques?

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Why

do you think petroleum ether, diethyl ether and acetone gives best separation of plant pigments?

Chlorophyll a is slightly soluble in a 7 : 2 : 0.05 mixture of petroleum ether, diethyl ether and acetone. Carotenoids are very soluble in this solvent system. These solubility differences will allow the separation of chlorophyll a from the carotenoids and chlorophyll b on a paper chromatogram.

Comment on the structure of pigments?

Why

application of sample is done as band and not spot?

to observe a more visible front rather than  just a speck Spots may get saturated while bands will widen and give clear zones. When

separated, pigments will appear as bands rather than smears so the calculations can be made easier;

Define the

following:

Extras

based on the number of polar groups between chlorophyll a and chlorophyll b, will chemically separate out on the paper Chlorophyll's central role in photosynthesis is harvesting light energy and its conversion to chemical energy Chlorophyll is the major lightabsorbing pigment in green plants.