Packaging and storage—
Preserve in well-closed, light-resistant containers.
Heavy metals, Method II 
231
:
0.002%.
Ordinary impurities 466—
Test solution:
methanol.
Standard solution:
methanol.
Application volume:
10 µL.
Eluant:
a mixture of toluene, ethyl acetate, and formic acid (50:45:5), in a nonequilibrated chamber.
Visualization:
1.
Organic volatile impurities, Method V 467:
meets the requirements.
Solvent—
Use dimethyl sulfoxide.
Assay—
Weigh accurately about 300 mg of Propylthiouracil, transfer to a 500-mL conical flask, and add 30 mL of water. Add from a buret about 30 mL of 0.1 N sodium hydroxide VS, heat to boiling, and agitate until solution is complete. Wash down any particles on the wall of the flask with a few mL of water, then add about 50 mL of 0.1 N silver nitrate while mixing, and boil gently for 7 minutes. Cool to room temperature, and continue to titrate with 0.1 N sodium hydroxide VS, determining the endpoint potentiometrically, using a glass-calomel electrode system. Each mL of 0.1 N sodium hydroxide is equivalent to 8.512 mg of C7H10N2OS.
;)
Propylthiouracil contains not less than 98.0 percent and not more than 100.5 percent of C7H10N2OS, calculated on the dried basis.
for 2 hours: it loses not more than 0.5% of its weight.