Ion-exchange chromatography separates solutes in a sample based on

Ion-exchange chromatography separates solutes in a sample based on

• A. Solubility of the solutes
• B. Sign and magnitude of the ionic charge
• C. Adsorption ability of the solutes
• D. Molecular size

Answer: (B)

Ion-exchange chromatography separates solutes by electrostatic interactions between charged groups on the stationary phase and the ions in the sample. The deciding factor is the charge of each solute—the sign (positive or negative) and how strong that charge is. Ions with a larger magnitude of charge bind more strongly to the opposite charge on the resin and are retained longer; ions with weaker or opposite interactions elute sooner. Changing the eluent conditions, such as salt concentration or pH, disrupts these ionic bonds and releases bound solutes in order of their affinity. This emphasizes why the charged nature of the solutes drives separation, rather than solubility, size, or adsorption alone. For example, on a cation-exchange column, divalent cations bind more strongly than monovalent ones and elute later when the elution strength is increased.

Ion-exchange chromatography separates solutes by electrostatic interactions between charged groups on the stationary phase and the ions in the sample. The deciding factor is the charge of each solute—the sign (positive or negative) and how strong that charge is. Ions with a larger magnitude of charge bind more strongly to the opposite charge on the resin and are retained longer; ions with weaker or opposite interactions elute sooner. Changing the eluent conditions, such as salt concentration or pH, disrupts these ionic bonds and releases bound solutes in order of their affinity. This emphasizes why the charged nature of the solutes drives separation, rather than solubility, size, or adsorption alone. For example, on a cation-exchange column, divalent cations bind more strongly than monovalent ones and elute later when the elution strength is increased.