(men'' a dye' one).
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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.
USP Reference standards 11
USP Menadione RS Click to View Structure
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.
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Monograph Sujatha Ramakrishna, Ph.D.
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(SM22010) Monographs - Small Molecules 2
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USP35–NF30 Page 3797
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