Determination of propylthiouracil using 1,3-dibromo-5,5-dimethylhydantoin (DBH): analytical methods of pharmacopeias with DBH in respect to environmental and economical concern: part 9.

USP 2000 [The United States Pharmacopeia, Rockville USA, 24th ed., 2000, pp. 1436] and PH. EUR. 1997 [European Pharmacopoeia, third ed., Council of Europe, Strasbourg, 1997, p. 1401] determine propylthiouracil using neutralization titration, whereby 0.1 M silver nitrate and twice boiling is necessary. With the application of 1,3-dibromo-5,5-dimethylhydantoin (DBH), the assay of propylthiouracil can be performed easily, faster and friendlier to environment. A mean deviation of 0.03% and a relative standard deviation of 0.3% are obtained. 5-Bromo-6-propyluracil is formed, when propylthiouracil is determined with DBH.