S 32.07

Sulfur.
Sulfur [7704-34-9].

Packaging and storage— Preserve in well-closed containers.

Identification— It burns in the air,forming sulfur dioxide,which can be recognized by its characteristic odor.

Reaction— Agitate 2.0g with 10mLof water,and filter:the filtrate is neutral to litmus.

Water,Method Iá921ñ: not more than 0.5%.

Residue on ignition á281ñ: not more than 0.3%.

Other forms of sulfur— Shake 1.0g with 5mLof carbon disulfide:it dissolves quickly,with the exception of a small amount of insoluble matter that is usually present.

Assay— Using about 60mg of Precipitated Sulfur,accurately weighed,proceed as directed under Oxygen Flask Combustion á471ñ,using a 1000-mLflask and using a mixture of 10mLof water and 5.0mLof hydrogen peroxide TSas the absorbing liquid.When the combustion is complete,fill the lip of the flask with water,loosen the stopper,then rinse the stopper,the sample holder,and the sides of the flask with water,and remove the stopper assembly.Heat the contents of the flask to boiling,and boil for about 2minutes.Cool to room temperature,add phenolphthalein TS,and titrate with 0.1Nsodium hydroxide VS.Perform a blank determination,and make any necessary correction.Each mLof 0.1Nsodium hydroxide is equivalent to 1.603mg of S.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 1838

Phone Number:1-301-816-8394