An impurity was separated by preparative liquid chromatography from fomulations containing anethole trithione, 5-(4-methoxyphenyl)-3H-1.2-dithiole-3-thione, and it was identified as inorganic sulfur. The sulfur content was determined by HPLC method and it was found that the-sulfur content in pharmaceutical grade raw material was as high as 5.0 w/w%.
