In size-exclusion chromatography, what feature of the resin is responsible for separating molecules by size?

In size-exclusion chromatography, what feature of the resin is responsible for separating molecules by size?

• A. Tiny pores in the beads.
• B. Immobilized enzymes on the column.
• C. Electrically charged gradient.
• D. Specific antibody-antigen interactions.

Answer: (A)

In size-exclusion chromatography, the separating feature is the porous beads in the resin. These tiny pores create a network that acts like a molecular sieve. Large molecules can’t enter many of the pores and thus travel through the column mainly via the outer, or void, volume, eluting first. Smaller molecules can enter more pores, which lengthens their path through the resin and delays their exit. This difference in accessible volume based on size is what allows separation by size. Other mechanisms—such as binding to immobilized enzymes (affinity), moving through a charged gradient (ion-exchange), or specific antibody–antigen interactions (affinity)—drive different types of separations, not size-based filtration.

In size-exclusion chromatography, the separating feature is the porous beads in the resin. These tiny pores create a network that acts like a molecular sieve. Large molecules can’t enter many of the pores and thus travel through the column mainly via the outer, or void, volume, eluting first. Smaller molecules can enter more pores, which lengthens their path through the resin and delays their exit. This difference in accessible volume based on size is what allows separation by size.

Other mechanisms—such as binding to immobilized enzymes (affinity), moving through a charged gradient (ion-exchange), or specific antibody–antigen interactions (affinity)—drive different types of separations, not size-based filtration.