In chromatography, which statement about the mobile phase is correct?

In chromatography, which statement about the mobile phase is correct?

• A. The phase that interacts with compounds and causes separation.
• B. The phase that moves through the stationary phase.
• C. The phase that remains fixed.
• D. The phase that dissolves solids.

Answer: (B)

In chromatography, separation happens because the solutes distribute between two phases: a stationary phase that stays in place and a mobile phase that flows through it. The defining feature of the mobile phase is that it moves through the column, carrying dissolved analytes with it and enabling different amounts of interaction with the stationary phase. That movement and differential partitioning cause the various compounds to elute at different times. So the correct statement is that the mobile phase is the phase that moves through the stationary phase. The other descriptions point to the stationary phase (the one that interacts with compounds and causes separation, or the one that remains fixed) or are too general (dissolving solids) to capture the essential role of the mobile phase in chromatography.

In chromatography, separation happens because the solutes distribute between two phases: a stationary phase that stays in place and a mobile phase that flows through it. The defining feature of the mobile phase is that it moves through the column, carrying dissolved analytes with it and enabling different amounts of interaction with the stationary phase. That movement and differential partitioning cause the various compounds to elute at different times.

So the correct statement is that the mobile phase is the phase that moves through the stationary phase. The other descriptions point to the stationary phase (the one that interacts with compounds and causes separation, or the one that remains fixed) or are too general (dissolving solids) to capture the essential role of the mobile phase in chromatography.