Chromatography Technique

it is based on Greek word, "kroma" means colour. This separation was first used for the separation of colour, hence it got this name.

Chromatography is a technique used to separate those solutes of a mixture which are soluble in the same solvent. It is used to separate the colored components of a natural dye. The separation of different components of a mixture depends on their solubilities in the same solvent.

It is a modern technique used for the separation of a mixture of substances which when separated, formed distinct coloured rings. These zones are named as chromatograms. These days, chromatography is applied to coloured as well as colourless substances for analysis.

Principle :-

The principle on which paper chromatography work is very simple. The pulp in the filter paper used for chromatography, is composed of thin threads acting as cappillaries. Different soluble dyes move upwards at different speeds and to different levels, by capillary action. In the laboratory, a fine quality of ordinary filter paper can also be used.

Working :-

Take a thin strip of filter paper and drop a blue ink on it at a distance of 2cm from the bottom.

Dip the lower end of the filter paper in water. The filter paper should be kept hanging.

You will observe, as the water rises on the paper it takes along with it the dye particles.

Dye is a mixture of colours. The coloured component which is more soluble in water, rises faster and so on. In this way, all the coloured components can be separated.

The rate of movement of each absorbed material depends upon :-

The relative solubility of the constituents of mixture in a given solvent.

The relative affinity of the constituents of mixture for the absorbent medium.

Example: Dye present in ink can be separated from ink by paper chromatography. The ink that is used has water as the solvent and dye is mixed in it to provide colour.

Depending upon the nature of the stationary and the mobile phases, the different types of chromatographic techniques commonly used are :-

Paper chromatography

Column chromatography

Thin layer chromatography

Gas chromatography

Application of Chromatography:

To separate drugs from blood.

To separate pigments from natural colours.

To separate colours in a dye.

Sample Questions

(More Questions for each concept available in Login)

Question : 1

Which of the following papers is used in the separation of dyes present in ink?
A. Simple paper		B. Chromatographic paper
C. Brown paper		D. Simple filter paper
Right Option : B
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Question : 2

_____________________ is a technique used to separate those solutes of a mixture which are soluble in the same solvent.
A. Chromatography	B. Centrifugation	C. Fractional distillation	D. All of these.
Right Option : A
View Explanation

Question : 3

The method that we use to separate drugs from blood is also used to separate pigments from natural colours. The name of this method is ________________
A. Crystallization	B. Chromatography	C. Evaporation	D. None of the above
Right Option : B
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