What principle governs the separation of components in chromatography?

• A. Separation based on solubility in water
• B. Separation based on differential affinity for a stationary phase versus a mobile phase
• C. Separation based on molecular weight only
• D. Separation based on chemical reactivity

Answer: (B)

The principle that governs the separation of components in chromatography is based on the differential affinity for a stationary phase versus a mobile phase. In this technique, a mixture is dissolved in a mobile phase, which carries the components through a stationary phase. The components interact differently with the stationary phase and the mobile phase, leading to varying rates of movement. Those that have a higher affinity for the stationary phase will move more slowly, while those with a greater affinity for the mobile phase will travel more quickly.

This variation in interaction causes the components to separate as they travel along the stationary phase. The effectiveness of this method relies on the differences in polarity, size, or other chemical properties of the components involved. Thus, B accurately describes the fundamental mechanism behind how chromatography separates substances.