Separation, analyses and syntheses of trimethoprim impurities

The analysis of several impurities of the chemotherapeutic agent trimethopr im with various methods, including thin layer chromatography. gas chromatog raphy, capillary electrophoresis as well as nuclear magnetic resonance is d escribed. These methods were used to identify new impurities in trimethopri m batches. The main impurities were separated by column chromatography. To ensure the identity of the impurities, de novo syntheses were successfully carried out. With the methods described, it was possible to detect, separat e and identify new impurities in trimethoprim batches.