How are separated substances collected in column chromatography?

In column chromatography, substances are separated based on their varying affinities for the stationary and mobile phases as they travel through a packed tube. As the mobile phase continuously flows through the column, components that are less attracted to the stationary phase move more rapidly and exit the column first, while those with stronger attractions remain longer.123

These separated components are collected as they exit the bottom of the column. In modern laboratory settings, particularly in liquid-solid chromatography, this process is often automated using a fraction collector, which systematically gathers the eluent as it emerges. Additionally, detectors are frequently placed on-line at the column exit to monitor, analyze, or quantify the components as they are eluted.132