Rhodamine 123 is a popular green fluorescent mitochondrial dye that stains mitochondria in living cells in a membrane potential-dependent fashion. It is widely used in flow cytometry studies involving mitochondrial membrane potential. Please also see Dihydrorhodamine 123 and its HCl salt.    &lamba;Ex/&lamba;Em(MeOH) = 505/534 nm  ε (505 nm, MeOH) = 97,000  Orange red solid soluble in DMSO or DMF  Store at 4°C and protect from light, especially in solution  C21H17ClN2O3  MW: 381  [62669-70-9]