Chromatography is a highly efficient analytical technique which primarily relies on the separation of components. This separation over a stationary phase happens under the influence of the mobile phase on the components.
But this separation on the stationary phase occurs by two physical methods like adsorption or partition.
Hence the term adsorption chromatography and partition chromatography are mentioned explicitly under the principle of separation.
But in general, adsorption is the method of separation when the stationary phase is solid. On the other hand, the partition is the method which occurs when the stationary phase is liquid.
Difference between Adsorption and Partition Chromatography
The primary difference is the physical interaction between the sample components and the mobile and stationary phases used.
Adsorption chromatography principle:
Here the sample components physically adsorb (stick) to the stationary phase. There is relatively no adsorption of the sample with the mobile phase. Mobile phase here just forces the sample particles to move over the stationary phase.
If the stationary phase is polar in nature, the polar component of the sample adsorbs to it while others move on.
Adsorption chromatography definition:
It is a process of separation of components of a mixture 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.
Based on nature, polar compounds adsorb with greater intensity to the polar stationary phase while non-polar compounds remain suspended in the mobile phase. Hence during separation of components, the nonpolar component comes out of the column first while the polar components elute out last due to greater adsorption.
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 seen only with solid stationary phase chromatography.
Partition chromatography is a process of separation which is based on the partition coefficient. Here the components of the mixture get distributed into two liquid phases. Here both the stationary phase and mobile phase are liquids. The components get partitioned in between two phase due to the differences in partition coefficients.
Polar molecules get partitioned into the polar phase to a maximum extent. The nonpolar molecules get partitioned into the non-polar liquid phase.
This mode of partition chromatography applies to Liquid-liquid, liquid-gas chromatography and not to solid-gas chromatography. Gases are freely flow-able hence, for them partition works better than adsorption.
Examples include paper chromatography, gas chromatography, high-performance thin layer chromatography (HPTLC), partition chromatography is the principle of separation.
In paper chromatography, the paper is in the solid state, but the pores in between the paper contain moisture which acts as a stationary liquid phase.