Fluorescein disodium salt

Fluorescein disodium salt is a water-soluble version of fluorescein. Fluorescein is a fluorophore commonly used in microscopy, flow cytometry forensics, serology to detect latent blood stains, and in dye tracing (attached to certain biologically active molecules). Fluorescein sodium salt has been utilized in studies as a drug model, as a penetrating dye and also as a fluorescen tracer. Fluorescein has an absorption maximum at 490 nm and emission maximum of 514 nm (in water). It has a pKa at 6.4 and multiple ionization equilibria. This leads to pH dependent absorption and emission over the range of 5 to 9. It has an isoabsorptive point at 460 nm. Spectral Data: lambdaEx=490nm, lambdaEm=514nm.