Principles of chromatography

Chromatography is based on the separation of sample components in a mixture. This separation takes place due to interactions between a stationary phase and a mobile phase. Depending on the strength of interaction, the compounds can be more attracted to the stationary or the mobile phase.

The speed of a migrating sample component depends on whether the component has an affinity for the stationary or mobile phase. This affinity appears via various actions: adsorption, partition, ion exchange, etc.

If the component has a higher affinity to the mobile phase, it will not spend too much time with the stationary phase and will be eluted quite fast. On the other hand, if the component has a higher affinity to the stationary phase, it will spend more time with the stationary phase and will be eluted later.

The result is that the amount of time a compound stays in the column is different based on its property. Differences in this time lead to the separation of the compounds in the starting mixture.