In ion-exchange chromatography, which molecules will attach to the beads?

In ion-exchange chromatography, which molecules will attach to the beads?

• A. Non-oppositely charged molecules attach to the beads.
• B. Molecules of opposite charge will attach to the beads.
• C. All molecules wash through without binding.
• D. Molecules are irreversibly bound regardless of charge.

Answer: (B)

In ion-exchange chromatography, the beads have fixed surface charges and attract molecules that carry the opposite charge through ionic interactions. Because of this, molecules with a charge opposite to the bead’s charge will attach to the beads. This binding is typically reversible and can be disrupted by changing the salt concentration or pH, which is how elution is achieved. Molecules with the same charge as the bead are not attracted by these ionic interactions and usually do not bind under normal conditions. The idea that all molecules wash through or that binding is irreversible regardless of charge isn’t accurate for standard ion-exchange behavior.

In ion-exchange chromatography, the beads have fixed surface charges and attract molecules that carry the opposite charge through ionic interactions. Because of this, molecules with a charge opposite to the bead’s charge will attach to the beads. This binding is typically reversible and can be disrupted by changing the salt concentration or pH, which is how elution is achieved. Molecules with the same charge as the bead are not attracted by these ionic interactions and usually do not bind under normal conditions. The idea that all molecules wash through or that binding is irreversible regardless of charge isn’t accurate for standard ion-exchange behavior.