Question

Distinguish between parllon & adsorption chromatography.

Answer 1

Adsorption chromatography principle:

Adsorption chromatography definition:

It is a process of separation of components in a mixture introduced into chromatography system based on the relative differences in adsorption of components to the stationary phase present in the chromatography column.

Here the molecules or components of the mixture travel with different rates due to differences in their affinity towards stationary phase. Adsorption means a physical attachment between the compound and the particles of stationary phase. Based on nature, polar compounds adsorb with stronger or greater intensity to the polar stationary phase while non-polar compounds adsorb better to the non-polar stationary phase than polar components. Hence during separation of components, when we use a polar stationary phase, polar components elute out late due to greater adsorption and non-polar components get out of the column or elute out first. This is exactly reverse on using a non-polar stationary phase.

This adsorption chromatography applies to only solid-liquid or solid-gas chromatography. Because the adsorption phenomenon is an inherent property of solids and hence it is used with only solid stationary phase chromatography.

Partition (coefficient) chromatography:

Partition chromatography is a process of separation whereby the components of the mixture get distributed into two liquid phases due to differences in partition coefficients during the flow of mobile phase in the chromatography column.

Here the molecules get preferential separation in between two phases. i.e., both stationary phase and mobile phase are liquid in nature. So molecules get dispersed into either phases preferentially. Polar molecules get partitioned into polar phase and vice-verse. This mode of partition chromatography applies to Liquid-liquid, liquid-gas chromatography and not to solid-gas chromatography. Because partition is the phenomenon in between a liquid and liquid or liquid and gas or gas and gas. But not in solid involvement.