||ROX dyes are strongly red fluorescent. They have longer excitation and emission wavelengths than the ?conventional? rhodamines. These dyes are used to label peptides, proteins, and other biological ligands. 5-ROX, 6-ROX and their mixture 5(6)-ROX are used to label biomolecules by EDC-mediated reactions. The ratio of 6-isomer/5-isomer is in the range 3/1 to 6/1. Compared to other rhodamines, ROX is very unstable. Cautions must be exercised to prevent the deterioration during storage.