What is a Locating Agent in Chromatography?

Definition of a Locating Agent in Chromatography:

A locating agent in chromatography is a chemical reagent used to detect and visualize separated compounds on a chromatographic medium. Locating agents react with colorless or invisible chromatographic spots to produce visible color changes on the stationary phase. In paper chromatography and thin-layer chromatography, locating agents are applied after separation to reveal the positions of analytes on the medium. Different locating agents selectively respond to specific functional groups, enabling visual identification of separated compounds.