Which statement about chromatography is TRUE?

Which statement about chromatography is TRUE?

• A. Partition chromatography is most appropriate to identifying analytes that may be distributed between two liquid phases.
• B. Steric exclusion chromatography is best suited for separating analytes based on their solubility in the mobile solvent.
• C. In liquid-solid chromatography, the stationary phase separates analytes based on size, shape, and polarity.
• D. Ion-exchange chromatography has a resin phase that is soluble to water and separation of the mixture is based on magnitude and charge of ionic species.

Answer: (A)

Chromatography separates components by how readily each one partitions between a mobile phase and a stationary phase. In partition chromatography, the stationary phase is a second liquid that is immiscible with the mobile phase, so analytes distribute themselves between the two liquids according to their affinities. This is why describing partition chromatography as best for compounds distributed between two liquid phases is correct. The other statements misstate the primary separation mechanisms. Size-exclusion (steric exclusion) relies on molecule size relative to the pores of the stationary phase, not solubility in the mobile solvent. In liquid-solid chromatography, separation is mainly due to interactions with the solid stationary phase—typically polarity and adsorption—rather than size or shape as the dominant factors. Ion-exchange chromatography uses an insoluble resin with charged groups; separation depends on ionic interactions and conditions like pH and ionic strength, not on the resin being soluble in water or simply on magnitude and charge.

Chromatography separates components by how readily each one partitions between a mobile phase and a stationary phase. In partition chromatography, the stationary phase is a second liquid that is immiscible with the mobile phase, so analytes distribute themselves between the two liquids according to their affinities. This is why describing partition chromatography as best for compounds distributed between two liquid phases is correct.

The other statements misstate the primary separation mechanisms. Size-exclusion (steric exclusion) relies on molecule size relative to the pores of the stationary phase, not solubility in the mobile solvent. In liquid-solid chromatography, separation is mainly due to interactions with the solid stationary phase—typically polarity and adsorption—rather than size or shape as the dominant factors. Ion-exchange chromatography uses an insoluble resin with charged groups; separation depends on ionic interactions and conditions like pH and ionic strength, not on the resin being soluble in water or simply on magnitude and charge.