Fluorescein

Absorption

Rapidly distributed

Description

Fluorescein is a synthetic organic compound available as a dark orange/red powder slightly soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications.
Fluorescein is a fluorophore commonly used in microscopy, in a type of dye laser as the gain medium, in forensics and serology to detect latent blood stains, and in dye tracing. Fluorescein has an absorption maximum at 494 nm and emission maximum of 521 nm (in water). The major derivatives are fluorescein isothiocyanate (FITC) and, in oligonucleotide synthesis, 6-FAM phosphoramidite.
Fluorescein also has an isosbestic point (equal absorption for all pH values) at 460 nm. Fluorescein is also known as a color additive (D&C Yellow no. 7). The disodium salt form of fluorescein is known as uranine or D&C Yellow no. 8.
The color of its aqueous solution varies from green to orange as a function of the way it is observed: by reflection or by transmission, as it can be noticed in bubble levels in which fluorescein is added as a colorant to the alcohol filling the tube to increase the visibility of the air bubble and the precision of the instrument. More concentrated solutions of fluorescein can even appear red.

Description

Fluorescein is an organic dye also known as D & C Yellow No. 7 and many other names. A. von Baeyer first synthesized it in 1871 from phthalic anhydride and resorcinol and called it resorcinphthalein. It is not soluble in water or many organic solvents, but its disodium salt (fluorescein sodium, uranine, D & C Yellow No. 8) is highly water-soluble.



Crystalline or powdered fluorescein is reddish orange, but in alkaline solution it has an intense yellow-green fluorescence. Because of its fluorescence, it was used to dye the Chicago River for St. Patrick’s Day, beginning in 1962. A few years later, it was replaced by a more environmentally friendly vegetable dye.

The Uses of Fluorescein

Fluorescein is used as a fluorescent tracer for many applications including in a type of dye laser as the gain medium, in forensics and serology to detect latent blood stains and in dye tracing. It is used to localise multiple muscular ventricular septal defects during open heart surgery and confirm the presence of any residual defects. It is applied to teeth to reveal plaque.

Background

A phthalic indicator dye that appears yellow-green in normal tear film and bright green in a more alkaline medium, such as the aqueous humor, and is used therapeutically as a diagnostic aid in corneal injuries and corneal trauma. It has been approved by FDA for use in externally applied drugs and cosmetics. (From Merck Index, 12th ed; American Medical Association Drug Evaluations; 1995, p2275)

Indications

For diagnostic imaging. Primarily indicated in diagnostic fluorescein angiography or angioscopy of the fundus and of the iris vasculature.

What are the applications of Application

Fluorescein (free acid) is the free acid form of fluorescein

Metabolism

Not Available