In thin-layer chromatography used for drug testing, what is the essential purpose of the solvent?

In thin-layer chromatography used for drug testing, what is the essential purpose of the solvent?

• A. To extract the drugs
• B. To visualize the spots with color
• C. To stabilize the sample
• D. To calibrate the plate

Answer: (A)

In thin-layer chromatography, the solvent serves as the mobile phase that dissolves the sample and carries its components up the plate. As the solvent front moves by capillary action, each component partitions between the mobile phase and the stationary phase (the silica on the plate). Components interact differently with the stationary phase, so they travel at different speeds and separate into distinct spots. This separation is what allows you to identify drugs by comparing their positions to standards. Visualization of the spots (with color or UV) happens after development, not as the solvent’s primary function. The solvent isn’t there to stabilize the sample or calibrate the plate.

In thin-layer chromatography, the solvent serves as the mobile phase that dissolves the sample and carries its components up the plate. As the solvent front moves by capillary action, each component partitions between the mobile phase and the stationary phase (the silica on the plate). Components interact differently with the stationary phase, so they travel at different speeds and separate into distinct spots. This separation is what allows you to identify drugs by comparing their positions to standards. Visualization of the spots (with color or UV) happens after development, not as the solvent’s primary function. The solvent isn’t there to stabilize the sample or calibrate the plate.