Calcein

Calcein, also known as fluorexon, fluorescein complex, is a fluorescent dye with an excitation and emission wavelengths of 495/515 nm, respectively. Calcein also self-quenches even at concentrations below 100mM. It is used as a complexometric indicator for titration of calcium ions with EDTA, and for fluorometric determination of calcium. It has the appearance of orange crystals.