Xylene Cyanol FF is primarily used as a tracking dye in agarose and polyacrylamide gel electrophoresis. It helps monitor the progress of nucleic acid or protein migration during electrophoresis, as it moves at a predictable rate relative to the molecules being separated. The dye is particularly useful in DNA and RNA analysis, where it serves as a visual marker to estimate the size of fragments and ensure the electrophoresis process is functioning correctly. Additionally, it is sometimes employed in combination with other dyes, such as Bromophenol Blue, to provide a broader range of tracking reference points. Its distinct blue color makes it easy to identify and track in gel systems.