6-FAM (full name: 6-Carboxyfluorescein, single isomer) is the free acid form of 6-carboxyfluorescein single isomer.    &lamba;Ex/&lamba;Em (pH 9) = 495/519 nm  Yellow orange solid soluble in water (pH>6), DMF or DMSO  Store at 4°C and protect from light  C21H12O7  MW: 376.3  [3301-79-9]