SUBSTANTIALLY PURE FLUORESCEIN Russian patent published in 2013 - IPC C07D493/10 

FIELD: chemistry.

SUBSTANCE: present invention relates to a sterile aqueous solution of fluorescein for angiography and a method of obtaining fluorescein with special impurity content. The disclosed solution contains 10-25 wt % fluorescein in form of a sodium salt, where the only impurity of resorcinol and fluorescein-related compounds with molecular weight of 258, 284, 346, 332, 424, 374 and 738 is present in amount of not more than 0.1 wt % fluorescein, or the total amount of said impurities is not more than 0.6 wt % fluorescein, and where content of chloride is less than 0.25 wt % fluorescein. Fluorescein with said nature of impurities is obtained by conducting deacetylation of commercial-grade fluorescein with an acetic anhydride as a reagent and a solvent to obtain O,O'-diacetyl fluorescein with purity of 99.7%; after basic hydrolysis of which activated carbon is added; filtered; ethanol is added to the filtrate until achieving ethanol-to-water ratio of 2:1; pH of the solution is brought to a value of 1.0-2.5 by adding HCl solution while cooling for 2-4 hours; the precipitate is filtered, washed with water and ethanol and dried.

EFFECT: fluorescein obtained using the method disclosed herein is slightly coloured, reduces hypertonicity of the solution for injection obtained therefrom, and also has low content of impurities which can be toxic or non-fluorescent.

7 cl, 20 dwg, 10 tbl, 8 ex