Which statement accurately describes the mobile phase in column chromatography?

Which statement accurately describes the mobile phase in column chromatography?

• A. It is a single polar solvent
• B. It is a single nonpolar solvent
• C. It has no effect on separation
• D. It can be a mixture of polar and nonpolar solvents

Answer: (D)

The mobile phase is the liquid that moves through the column and carries the sample past the stationary phase, and its polarity relative to the stationary phase controls how strongly each component is retained. By adjusting what the mobile phase is made of, you change the balance between solubility in the moving solvent and interaction with the column packing. Using a mixture of polar and nonpolar solvents lets you finely tune elution strength and selectivity, which is essential for separating components with a range of polarities. A single solvent can work, but mixtures—or gradients—give much better control over the separation. That’s why the statement that the mobile phase can be a mixture of polar and nonpolar solvents is the best description.

The mobile phase is the liquid that moves through the column and carries the sample past the stationary phase, and its polarity relative to the stationary phase controls how strongly each component is retained. By adjusting what the mobile phase is made of, you change the balance between solubility in the moving solvent and interaction with the column packing. Using a mixture of polar and nonpolar solvents lets you finely tune elution strength and selectivity, which is essential for separating components with a range of polarities. A single solvent can work, but mixtures—or gradients—give much better control over the separation. That’s why the statement that the mobile phase can be a mixture of polar and nonpolar solvents is the best description.