What principle does chromatography rely on?

Chromatography operates on the principle of separating mixtures based on their different affinities for two phases: a stationary phase and a mobile phase. The stationary phase is typically a solid or a viscous liquid that remains fixed in place, while the mobile phase is a liquid or gas that moves through or over the stationary phase.

When a mixture is introduced into the chromatographic system, the different components interact with the stationary and mobile phases to varying degrees. Those components that have a higher affinity for the stationary phase will move more slowly, while those with a stronger attraction to the mobile phase will travel faster. This differential movement allows for the separation of the components as they pass through the system, ultimately leading to their collection at different points.

By exploiting these differing interactions, chromatography can effectively isolate and identify various substances within a mixture, making it an invaluable technique in chemical analysis and purification.