1,3,6,8-Pyrenetetrasulfonic acid tetrasodium salt hydrate is a fluorescent probe and pH indicator. It fluoresces blue in acidic solutions and in acidic organelles but fluoresces green in more basic organelles. This compound is potentially useful as a coloring agent, biological stain, optical detecting reagent.
1. E. Koller Appl. Fluoresc. Technol. 1, 13, (1989); 2. N. Kobayashi J. Chem. Soc., Chem. Commun., 918, (1988)