Phenylmercuric Acetate

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

DOWNLOAD PDF HERE

C₈H₈HgO₂ 336.74

Mercury, (acetato-O)phenyl-;

(Acetato)phenylmercury CAS RN®: 62-38-4.

1 DEFINITION

Phenylmercuric Acetate contains NLT 98.0% and NMT 100.5% of phenylmercuric acetate (C₈H₈HgO₂).

2 IDENTIFICATION

A. Sample: 0.1 g

Analysis: To the Sample add 0.5 mL of nitric acid. Warm gently until a dark brown color is produced, and dilute with water to 10 mL.

Acceptance criteria: The characteristic odor of nitrobenzene is evolved.

B. Sample: 0.1 g

Analysis: To the Sample add 0.5 mL of sulfuric acid and 1 mL of alcohol, and warm.

Acceptance criteria: The characteristic odor of ethyl acetate is evolved.

C. Sample solution: Saturated solution in water

Analysis: To 5 mL of the Sample solution add a few drops of sodium sulfide TS.

Acceptance criteria: A white precipitate is formed, which turns black when the mixture is boiled and then allowed to stand.

3 ASSAY

3.1 Procedure

Sample solution: Transfer 500 mg of Phenylmercuric Acetate 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, and then add 500 mg 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.

3.2 Titrimetric system

(See Titrimetry 〈541〉.)

Mode: Direct titration

Titrant: 0.1 N ammonium thiocyanate VS

Endpoint detection: Visual

Analysis: Titrate with Titrant, and each mL of 0.1 N ammonium thiocyanate is equivalent to 16.84 mg of phenylmercuric acetate (C₈H₈HgO₂).

Acceptance criteria: 98.0%–100.5%

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.2%

Polymercurated Benzene Compounds

Sample solution: Shake 2.0 g of Phenylmercuric Acetate with 100 mL of acetone, and filter.

Analysis: Wash the residue with successive portions of acetone until a total of 50 mL is used, then dry the residue at 105° for 1 h. Weigh the residue.

Acceptance criteria: NMT 1.5%; the weight of residue is NMT 30 mg.

5 SPECIFIC TESTS

Melting Range or Temperature 〈741〉: 149°–153°

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers.