Which chromatography method separates components based on charge?

• A. Size-Exclusion Chromatography
• B. Ion Exchange Chromatography (IEC)
• C. Affinity Chromatography
• D. Gas Chromatography

Answer: (B)

Ion exchange chromatography separates components according to their charge by using a stationary phase with fixed charged groups. Molecules with the opposite charge to the resin bind to the column, while those with the same charge or neutral species move through more quickly. By choosing a cation exchanger, positively charged molecules are captured, whereas an anion exchanger binds negatively charged ones. Elution is achieved by increasing salt concentration or altering pH to disrupt these electrostatic interactions, releasing bound species in order of their charge and affinity. Other methods separate by different properties: size-exclusion chromatography relies on molecular size; affinity chromatography depends on specific binding to a ligand; and gas chromatography separates volatile compounds based on volatility and interactions with the stationary phase, not charge.