Rapid and sensitive LC separation of new impurities in trimethoprim

Trimethoprim is a chemotherapeutic often used in combination with sulfonami des. Herein, we report on the development and validation of a new HPLC assa y of trimethoprim. The test allows the identification of new impurities tha t have not been detectable with any other known method including European P harmacopoeia and USP. Trimethoprim and its impurities were eluted on a C18 column with a mobile phase consisting of methanol and a solution of sodium perchlorate at a flow rate of 1.3 ml/min and was quantified by UV detection at 280 nm. Overall, the method is simple, rapid and reliable for the detec tion of six impurities in trimethoprim batches. (C) 2001 Elsevier Science B .V. All rights reserved.