Gel Permeation Chromatography is an another type of column chromatography.
It has a slight modification in that the column is filled or packed with a stationary phase which can act as a molecular sieves.
Hence it is also called Molecular-sieve chromatography.
A porous material is used as stationary phase while a liquid as the mobile phase.
The diameters of the pore are in the order few armstrongs similar to that of molecules.
Gel Permeation Chromatography Principle
Here the principle involved is that sample particles move through the column under the influence of mobile phase based on their relative physical size or mass.
Those particles with smaller size or mass move through the all possible pores due to their small size. Hence, they travel a longer path and get eluted last.
But large the larger particles traverse only through few possible pores due to their size. Hence, they travel shorter path and pass out of the column first.
Since the particles are separated by sizes, it is called as size exclusion chromatography.
This technique is called by different names like the gel filtration, exclusion chromatography.
1. The dry gel powder is allowed to swell in the solvent used as mobile phase. This powder absorbs the solvent and bulges to form a gel matrix. This gel matrix has molecular sieves to permit smaller particles.
2. The gel then is packed into the column to a sufficient height.
3. The mixture to be separated is mixed in the mobile phase and then poured over the top of the column. Further mobile phase is passed to let the mixture percolate through the gel matrix in the column.
4. The outlet eluate is collected in different beakers based on suitable time intervals to obtain size differentiated elutes separately.
♣ Helps determine the molecular weight distribution of polymers.
♣ It can be used as a general purification process for any sample.
♣ Since organic compounds like sugars, polypeptides, polystyrenes, etc. are of different size; this chromatography can be used to separate them.
♣ Since the substances are separated based on the mass of this method of chromatography helps in molecular weight determination.