Important Properties of Gels for Chromatography:

Out of different gels known only relatively few are suitable for chromatographic work. Some necessary requirements should be met through these gels to be useful for the said purpose. These are as follows.

i) Matrix of gel should be inert

Any interaction between the gel material and the solute may lead to irreversible binding of the solute. The interaction may lead to chemical alteration of labile substances. In biochemistry, there is a risk of denaturation of proteins and nucleic acids. If the right material is there, gel filtration chromatography is one of the few separation methods which are capable of giving quantitative yields.

ii) Gel must be chemically stable

The gel should be stable over a wide range of pH and temperature. The gels that are used in practice are stable over years and months. The leaching of material from bed should be very low.

iii) Low content of ionic groups

A low content of ionic groups is required to avoid ion exchange effects. Charged groups will give bad yields of charged solute and asymmetric elution curve. It is impossible to prevent the charged groups but the commercially available gels have extremely low ionic groups.

iv) Availability of huge choice of gels

For the adaption of a method of different problems, a wide choice of gels with same general composition but different fractionation ranges should be available. For microreticular gels, the fractionation range is mainly determined through the swelling properties. Gels with low content of dry substance in the gel provide access to larger molecular weight molecules than those with high contents of dry substance.

Along with macroreticular gels, the content of the dry substance is no longer the only variable which determines the fractionation range of the gel. The structure of the gel is also important.