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Ensulizole
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C13H10N2O3S 274.30

1H-Benzimidazole-5-sulfonic acid-2-phenyl-.
2-Phenylbenzimidazole-5-sulfonic acid [27503-81-7].
» Ensulizole contains not less than 98.0 percent and not more than 102.0 percent of C13H10N2O3S, calculated on the dried basis.
Packaging and storage— Preserve in tight containers in a cool place.
USP Reference standards 11— USP Ensulizole RS.
Identification—
Solution: 5 µg per mL, prepared as follows. Transfer about 100 mg of Ensulizole, accurately weighed, to a 100-mL volumetric flask, dissolve in 4 mL of 1 N sodium hydroxide, and dilute with water to volume. Transfer 0.5 mL of the solution to a 100-mL volumetric flask, dilute with water to volume, and mix.
Absorptivities, calculated on the dried basis, at the wavelength of maximum absorbance at about 302 nm, do not differ by more than 3.0%.
Loss on drying 731— Dry it at 105 for 4 hours: it loses not more than 2.0% of its weight.
Residual solvents 467: meets the requirements.
(Official January 1, 2007)
Assay— Transfer about 1200 mg of Ensulizole, accurately weighed, to a 300-mL iodine flask, and dissolve by stirring in 25 mL of 0.5 N sodium hydroxide. Add phenolphthalein TS, and titrate the excess with 0.5 N hydrochloric acid VS. Perform a blank determination, and make any necessary correction. Each mL of 0.5 N sodium hydroxide is equivalent to 137.15 mg of C13H10N2O3S. Calculate the percentage of C13H10N2O3S in the portion of Ensulizole taken by the formula:
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in which VNaOH is the volume, in mL, of 0.5 N sodium hydroxide added; TNaOH is the titer of the 0.5 N sodium hydroxide; VHCl is the volume, in mL, of 0.5 N hydrochloric acid used; THCl is the titer of 0.5 N hydrochloric acid; W is the weight, in g, of Ensulizole taken; and LOD is the percentage of loss on drying, as determined in the test for Loss on drying.
Auxiliary Information— Staff Liaison : Behnam Davani, Ph.D., MBA, Senior Scientist
Expert Committee : (MDAA05) Monograph Development-Antivirals and Antimicrobials
USP29–NF24 Page 802
Pharmacopeial Forum : Volume No. 31(5) Page 1363
Phone Number : 1-301-816-8394