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(organic chemistry)
C20H12O5 A yellowish to red powder, melts and decomposes at 290°C, insoluble in water, benzene, and chloroform, soluble in glacial acetic acid, boiling alcohol, ether, dilute acids, and dilute alkali; used in medicine, in oceanography as a marker in sea water, and in textiles to dye silk and wool.



a dye; yellow crystals. Fluorescein is poorly soluble in water; it dissolves better in alcohols and dilute alkalies. Decomposition occurs at the melting point, 314°–316°C. In aqueous solutions, fluorescein exists as a 1:1 mixture of the benzoid (I) and quinoid forms and has a strong yellow-green fluorescence (hence the name). Its structural form is

Fluorescein belongs to a group of triarylmethane (xanthene) dyes. It colors silk and wool yellow but is not used in the textile industry because of poor colorfastness. It is used to trace the course of underground waters. Its disodium salt (uranine) is a component of fluorescing mixtures, and its isothiocyanate derivatives are used as biological stains for identifying antigens and antibodies. Some halogen-substituted fluoresceins, such as eosins, also have practical value.

Fluorescein is produced by the condensation of phthalic anhydride with resorcinol.

References in periodicals archive ?
The visualization set-up requires the utilization of fluids which are transparent and able to solubilize the fluoresceine marker.
After 4 h in the primary antibody at room temperature, the sections were rinsed three times (5 min each) in TBS, and secondary antibody - fluoresceine isothiocyanate-conjugated goat anti-mouse IgG (FITC-GAM IgG) - was then applied to the sections; incubation continued for 2 h, at room temperature, in the dark.
In-situ fluoresceine impregnated rock thin sections were thus analyzed under fluorescence microscopy equipped with a Universal stage; the existing rock cracks were classified according to their host grain, textural position (inter or intragranular) and state (open, healed, and sealed), (Schild, 1999).

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