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C11H8O2 172.18

1,4-Naphthalenedione, 2-methyl-.
2-Methyl-1,4-naphthoquinone [58-27-5].
» Menadione contains not less than 98.5 percent and not more than 101.0 percent of C11H8O2, calculated on the dried basis.
Caution—Menadione powder is irritating to the respiratory tract and to the skin, and a solution of it in alcohol is a vesicant.
Packaging and storage— Preserve in well-closed, light-resistant containers. Store at 25, excursions permitted between 15 and 30.
B: Ultraviolet Absorption 197U
Solution: 5 µg per mL.
Medium: alcohol.
Absorptivities at 250 nm, calculated on the dried basis, do not differ by more than 3.0%.
Melting range, Class I 741: between 105 and 107.
Loss on drying 731 Dry it over silica gel for 4 hours: it loses not more than 0.3% of its weight.
Residue on ignition 281: not more than 0.1%.
Ordinary impurities 466
Test solution: methanol.
Standard solution: methanol.
Eluant: chloroform.
Visualization: 1.
Assay— Accurately weigh about 150 mg of Menadione, and transfer to a 150-mL flask. Add 15 mL of glacial acetic acid and 15 mL of 3 N hydrochloric acid, and rotate the flask until the Menadione is dissolved. Then add about 3 g of zinc dust, close the flask with a stopper bearing a Bunsen valve, shake, and allow to stand in the dark for 1 hour, with frequent shaking. Rapidly decant the solution through a pledget of cotton into another flask, immediately wash the reduction flask with three 10-mL portions of freshly boiled and cooled water, add 0.1 mL of orthophenanthroline TS, and immediately titrate the combined filtrate and washings with 0.1 N ceric sulfate VS. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N ceric sulfate is equivalent to 8.609 mg of C11H8O2.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Sujatha Ramakrishna, Ph.D.
(MDCV05) Monograph Development-Cardiovascular
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 2877
Pharmacopeial Forum: Volume No. 29(5) Page 1531