The gel was used as the stationary phase in the dimensional exclusion column. It ACTS like a molecular sieve, but the pore size of a gel is much larger than that of a molecular sieve, usually ranging from nanometers to hundreds of nanometers. Solutes are separated not by the force of their interaction between the two phases, but by the size of the molecules. Separation is only related to the pore size distribution of the gel and the fluid mechanics volume or molecular size of the solute. After entering the column, the sample flows through the external gels and pores with the mobile phase. In the sample, some molecules that are too large cannot enter the gel hole and are blocked, so they go directly through the column and appear first on the chromatogram. Some small molecules can enter all the gel holes and penetrate into the particles. These components have the largest retention value on the column and appear last on the chromatogram.