What principle does chromatography operate on?

Chromatography operates on the principle of separating components based on their rates of movement through different phases. In a typical chromatography setup, a stationary phase (such as a solid or a viscous liquid) is used alongside a mobile phase (which is a liquid or gas). As the mixture moves through the stationary phase, the various components interact differently with the phases due to factors like polarity, size, or affinity to the stationary phase. This difference in interaction causes some substances to travel faster and others to slow down, leading to their separation over time.

For example, in paper chromatography, components with a stronger affinity for the stationary phase will move more slowly, while those with a weaker affinity will move faster. This principle allows for the distinct separation of compounds in a mixture, which is a fundamental aspect of analytical chemistry.