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Nitromersol Topical Solution
»Nitromersol Topical Solution yields,from each 100mL,not less than 180.0mg and not more than 220.0mg of Nitromersol (C7H5HgNO3).
Dissolve the Sodium Hydroxide and the monohydrated Sodium Carbonate in 50mLof Purified Water,add the Nitromersol,and stir until dissolved.Gradually add Purified Water to make 1000mL.
NOTE—Prepare dilutions of Nitromersol Topical Solution as needed,since they tend to precipitate upon standing.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
A:
To 100mLadd 3mLof 3Nhydrochloric acid:a yellowish precipitate is formed.Filter,and retain both the filtrate and the precipitate.
B:
Add the precipitate from Identificationtest Ato 20mLof water and 2.5mLof 1Nsodium hydroxide.Add 500mg of sodium hydrosulfite,and heat to boiling:a heavy deposit of metallic mercury is formed.
Specific gravity á841ñ:
between 1.005and 1.010.
Mercury ions—
To the filtrate obtained in Identificationtest Aadd an equal volume of hydrogen sulfide TS:no darkening in color is produced,although a small amount of a flocculent,light yellow precipitate may be formed.
Assay—
Transfer 50.0mLof Topical Solution to a 500-mL Kjeldahl flask,add a few glass beads,and evaporate to about 5mL.Proceed as directed in the Assayunder Nitromersol,beginning with “Add 15mLof sulfuric acid.”
Auxiliary Information—
Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 1388
Phone Number:1-301-816-8394
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