Silica gels are amorphous forms of silica that consist of irregular 3-dimensional structures. They are porous materials with microscale to nanoscale pores. 

Silica gel is one of the most widely used packaging materials.

When you choose packing materials for HPLC, you must know the properties of each component to separate or purify.

Including size, its polarity or affinity, hydrophilic or hydrophobic.

We must choose the silica according to the materials being separated.