Which statement best describes the principle behind chromatography as used by Tsvet?

Which statement best describes the principle behind chromatography as used by Tsvet?

• A. Separation based on differential color intensity.
• B. Separation based on magnetic properties.
• C. Separation based on radioactive labeling.
• D. Separation based on differential adsorption of components to a stationary phase.

Answer: (D)

Chromatography works because different substances in a mixture interact differently with a solid surface (the stationary phase) and with the moving solvent (the mobile phase). In Tsvet’s plant pigment separations, the pigments are held on a solid adsorbent, and as the solvent flows through, each pigment’s tendency to stick to the solid vs stay in the liquid dictates how far it moves. Pigments that bind more weakly to the stationary phase travel farther with the solvent, while those that bind more strongly lag behind. This differential adsorption to the stationary phase is what produces the separation, unlike methods relying on color intensity, magnetic properties, or radioactive labeling.

Chromatography works because different substances in a mixture interact differently with a solid surface (the stationary phase) and with the moving solvent (the mobile phase). In Tsvet’s plant pigment separations, the pigments are held on a solid adsorbent, and as the solvent flows through, each pigment’s tendency to stick to the solid vs stay in the liquid dictates how far it moves. Pigments that bind more weakly to the stationary phase travel farther with the solvent, while those that bind more strongly lag behind. This differential adsorption to the stationary phase is what produces the separation, unlike methods relying on color intensity, magnetic properties, or radioactive labeling.