Among chromatographic principles, which is not typically considered a mechanism?

Among chromatographic principles, which is not typically considered a mechanism?

• A. Partition
• B. Absorption
• C. Adsorption
• D. Ion-exchange

Answer: (B)

At the heart of chromatography is how the analyte distributes between the mobile phase and the stationary phase. The main mechanisms described are partition, where the analyte dissolves into a second liquid-like phase within the stationary phase; adsorption, where it sticks to the surface of the stationary phase through surface interactions; and ion-exchange, where it swaps ions with charged groups on the stationary phase. Absorption would involve the analyte being taken up into the bulk of the stationary phase rather than interacting just with a surface or a separate phase. In most practical chromatography, retention is explained in terms of surface interactions (adsorption), distribution into a second phase (partition), or ionic interactions (ion-exchange). Absorption into the interior of the solid isn’t treated as a separate, defining mechanism for separation, so it’s not typically considered a standalone mechanism.

At the heart of chromatography is how the analyte distributes between the mobile phase and the stationary phase. The main mechanisms described are partition, where the analyte dissolves into a second liquid-like phase within the stationary phase; adsorption, where it sticks to the surface of the stationary phase through surface interactions; and ion-exchange, where it swaps ions with charged groups on the stationary phase. Absorption would involve the analyte being taken up into the bulk of the stationary phase rather than interacting just with a surface or a separate phase. In most practical chromatography, retention is explained in terms of surface interactions (adsorption), distribution into a second phase (partition), or ionic interactions (ion-exchange). Absorption into the interior of the solid isn’t treated as a separate, defining mechanism for separation, so it’s not typically considered a standalone mechanism.