Trimethoprim EP Impurity J

Trimethoprim EP Impurity J is a dihydroxybenzoyl derivative featuring a substituted pyrimidine ring and a para-hydroxybenzoic acid moiety, linked via an ether bridge. Its structure retains the core aromatic framework of trimethoprim but lacks the secondary amine functionality, introducing two additional hydroxyl groups on the benzoyl ring. This impurity arises from oxidative degradation of the parent compound, specifically targeting the methylene bridge between the pyrimidine and benzoyl units. It serves as a critical HPLC reference standard for quantifying process-related impurities in trimethoprim formulations.