5-(and-6)-FAM (full name: 5-(and-6)-Carboxyfluorescein mixed isomer) has a pKa of 6.5 and can be used as a pH indicator. Its excitation spectrum and fluorescence response to pH are similar to those of BCECF. Carboxyfluorescein can also be used as a tracer dye. The dye is membrane-impermeant and can be loaded into cells by microinjection or scrape loading.
- λEx/λEm (pH 9) = 492/514 nm
- λµ (pH 9) = 82,000
- Yellow orange solid soluble in pH>6 water
- Store at 4°C and protect from light, especially in solution
- MW: 376