Sublimed Sulfur
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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)
S 32.07
Sulfur CAS RN®: 7704-34-9; UNII: 70FD1KFU70.
1 DEFINITION
Sublimed Sulfur, dried over phosphorus pentoxide for 4 h, contains NLT 99.5% and NMT 100.5% of sulfur (S).
2 IDENTIFICATION
A. It burns in the air to sulfur dioxide, which can be recognized by its characteristic odor.
3 ASSAY
Procedure
Sample: 60 mg of Sublimed Sulfur previously dried over phosphorous pentoxide for 4 h
Titrimetric system
Mode: Direct titration
Titrant: 0.1 N sodium hydroxide VS
Endpoint detection: Visual
Analysis: Proceed as directed in oxygen Flask Combustion 〈471〉, using a 1000-mL flask and using a mixture of 10 mL of water and 5.0 mL of Hydrogen peroxide TS as the absorbing liquid. When the combustion is complete, fill the lip of the flask with water; loosen the stopper; then rinse the stopper, sample holder, and sides of the flask with water; and remove the stopper assembly. Heat the contents of the flask to boiling, and boil for about 2 min. Cool to room temperature, add phenolphthalein TS, and titrate with Titrant. Perform a blank determination and make any necessary correction. Each mL of 0.1 N sodium hydroxide is equivalent to 1.603 mg of sulfur (S).
Acceptance criteria: 99.5%–100.5% dried over phosphorous pentoxide for 4 h
4 IMPURITIES
Residue on Ignition 〈281〉: NMT 0.5%
Change to read:
Arsenic 〈211〉, Procedures, Procedure 1 (CN 1-Jun-2023)
Test preparation: Digest 750 mg of Sublimed Sulfur with 20 mL of 6 N ammonium hydroxide for 3 h, filter, and evaporate the clear filtrate on a steam bath to dryness. Add 15 mL of 2 N sulfuric acid and 1 mL of 30% hydrogen peroxide solution, evaporate to strong fumes of sulfur trioxide, and cool. Add cautiously 10 mL of water, and again evaporate to strong fumes, repeating, if necessary, to remove any trace of hydrogen peroxide. Cool, and dilute cautiously with water to 35 mL.
Acceptance criteria: NMT 4 ppm
5 SPECIFIC TESTS
Solubility in Carbon Disulfide
Sample: 1 g
Acceptance criteria: The Sample dissolves slowly and usually incompletely in about 2 mL of carbon disulfide.
6 ADDITIONAL REQUIREMENTS
Packaging and Storage: Preserve in well-closed containers.
