Sublimed Sulfur
S 32.07

Sulfur [7704-34-9].
» Sublimed Sulfur, dried over phosphorus pentoxide for 4 hours, contains not less than 99.5 percent and not more than 100.5 percent of S.
Packaging and storage— Preserve in well-closed containers.
Solubility in carbon disulfide— One g dissolves slowly and usually incompletely in about 2 mL of carbon disulfide.
Identification— It burns in the air to sulfur dioxide, which can be recognized by its characteristic odor.
Residue on ignition 281: not more than 0.5%.
Arsenic, Method I 211 Prepare the Test Preparation as follows. Digest 750 mg of Sublimed Sulfur with 20 mL of 6 N ammonium hydroxide for 3 hours, 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 percent hydrogen peroxide solution, evaporate to strong fumes of sulfur trioxide, 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. The limit is 4 ppm.
Assay— Proceed as directed under Oxygen Flask Combustion 471, using a 1000-mL flask and using about 60 mg of Sublimed Sulfur, previously dried over phosphorus pentoxide for 4 hours and accurately weighed, as the sample and 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 minutes. Cool to room temperature, add phenolphthalein TS, and titrate with 0.1 N sodium hydroxide VS. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N sodium hydroxide is equivalent to 1.603 mg of S.
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Monograph Behnam Davani, Ph.D., M.B.A.
Senior Scientist
(MDAA05) Monograph Development-Antivirals and Antimicrobials
USP32–NF27 Page 3637