Availability of gels with different particle size:

The particle size distribution should be very carefully controlled. A column of small particle size will generally give good resolution. If the particle size is increased, the reasons for zone broadening are amplified. With large particles the diffusion in and out of the particle takes longer. Flow pattern in large particles is inferior. On the other hand, the resistance to flow in a bed of large particle is lower. Thus, a compromise with regard to particle size should be reached giving maximum zone resolution under the desired flow conditions. Commonly, the commercial available gels are in bead forms.

Mechanical rigidity of the gel particles:

The mechanical rigidity of the gel grains should be as high as possible; otherwise they tend to be deformed by the forces caused by the flow of liquid. The force may cause the bead to compact reversibly or irreversibly, thus, increasing the flow through the bed. The microreticular gels along with small content of dry substance; a correspondingly high exclusion limit, tend to be mechanically weak. A single approach to solve the problem is to synthesize gels with a macroreticular structure and with a microreticular gel in the pores of macroreticular gel. Fractionations ranges are controlled through the microreticular gel in the pores although the aggregates of macroreticular gel take care of the mechanical strength. These gels are known as macro-microreticular gels.