Phenylmercuric Nitrate
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
Mercury, (nitrato-O)phenyl-;
Nitratophenylmercury
CAS RN®: 55-68-5.
1 DEFINITION
Phenylmercuric Nitrate is a mixture of phenylmercuric nitrate and phenylmercuric hydroxide containing NLT 87.0% and NMT 87.9% of phenylmercuric ion (C6H5Hg+ ), and NLT 62.75% and NMT 63.50% of mercury (Hg).
2 IDENTIFICATION
A.
Sample: 0.1 g
Analysis: To the Sample add 3 mL of sulfuric acid.
Acceptance criteria: The mixture becomes yellow, and the characteristic odor of nitrobenzene is evolved.
B.
Sample solution: Saturated solution in water
Analysis: To 5 mL of the Sample solution add 1 mL of 3 N hydrochloric acid.
Acceptance criteria: A white precipitate is formed.
C.
Sample solution: Saturated solution in water
Analysis: To 5 mL of the Sample solution add 5 mL of ammonium sulfide TS.
Acceptance criteria: There is no reaction in the cold, but upon heating in a boiling water bath for 10 min, a black precipitate is formed.
3 ASSAY
Phenylmercuric Ions
Sample: 200 mg
Analysis: Dissolve the Sample in 90 mL of water and 10 mL of nitric acid. Add 2 mL of ferric ammonium sulfate TS. Titrate with 0.05 N ammonium thiocyanate VS. Each mL of 0.05 N ammonium thiocyanate is equivalent to 13.88 mg of phenylmercuric ion (C6H5Hg+).
Acceptance criteria: 87.0%–87.9% of phenylmercuric ion Mercury
Sample solution: Transfer 400 mg of Phenylmercuric Nitrate to a 100-mL flask. Add 15 mL of water, 5 mL of formic acid, and 1 g of zinc dust, and reflux for 30 min. Cool. Filter, and wash the filter paper and the amalgam with water until the washings are no longer acid to litmus.
Dissolve the amalgam in 40 mL of 8 N nitric acid. Heat on a steam bath for 3 min, then add 0.5 g of Urea and enough potassium permanganate TS to produce a permanent pink color. Cool. Decolorize the solution with Hydrogen peroxide TS, and add 1 mL of ferric ammonium sulfate TS.
Analysis: Titrate with 0.1 N ammonium thiocyanate VS. Each mL of 0.1 N ammonium thiocyanate is equivalent to 10.03 mg of Hg.
Acceptance criteria: 62.75%–63.50% of mercury
4 IMPURITIES
Residue on Ignition 〈281〉: NMT 0.1%
5 SPECIFIC TESTS
Mercury Ions
Sample solution: Saturated solution in water
Analysis: To 5 mL of the Sample solution add 5 mL of 1 N sodium hydroxide.
Acceptance criteria: No yellow precipitate is formed (mercuric ions), and the solution does not darken (mercurous ions).
6 ADDITIONAL REQUIREMENTS
Packaging and Storage: Preserve in tight, light-resistant containers.
