What is the mobile phase in TLC?

What is the mobile phase in TLC?

• A. A mixture of polar and nonpolar solvents
• B. Pure water
• C. Polar solvent only
• D. Nonpolar solvent only

Answer: (A)

In TLC, the mobile phase is the solvent system that travels up the plate and carries the sample with it. The speed at which each component moves depends on how strongly it sticks to the stationary phase (the solid coating on the plate) versus how well it dissolves in the solvent. Because different compounds have different interactions with the stationary phase, you tune the eluent’s polarity to separate them effectively. That’s why the mobile phase is usually a mixture of polar and nonpolar solvents—you can adjust their ratio to set the overall polarity and elution strength to achieve good separation. Pure water isn’t typical for normal-phase TLC because it’s too polar and interacts strongly with the silica, often hindering movement; a single polar or a single nonpolar solvent generally won’t provide the right balance for most separations. A mixture gives the control needed to elute different compounds at different rates.

In TLC, the mobile phase is the solvent system that travels up the plate and carries the sample with it. The speed at which each component moves depends on how strongly it sticks to the stationary phase (the solid coating on the plate) versus how well it dissolves in the solvent. Because different compounds have different interactions with the stationary phase, you tune the eluent’s polarity to separate them effectively. That’s why the mobile phase is usually a mixture of polar and nonpolar solvents—you can adjust their ratio to set the overall polarity and elution strength to achieve good separation. Pure water isn’t typical for normal-phase TLC because it’s too polar and interacts strongly with the silica, often hindering movement; a single polar or a single nonpolar solvent generally won’t provide the right balance for most separations. A mixture gives the control needed to elute different compounds at different rates.