Characterization of related impurities in cefotetan bulk material by high-performance liquid chromatography-electrospray tandem mass spectrometry

LC/MS methods were developed for rapid identification of 4 impurities in cefotetan. Based on the degradation mechanism of Cephalosporins , stress tests were designed and performed, and it was found that two main impurites were base degradation products. Cefotetan disodium bulk material was separated on a C18 column, with 1% ice acetate solution-acetonitrile-methanol (80:10:10) as mobile phase. Under the negative ion mode, four impurities were separated from cefotetan components and identified on the basis of MS/MS spectra and the proposed general fragmentation pathway of cefotetan, as well as the UV spectra. Four impurites were characterized as 5-mercapto-1-methyl-tetrazole, cefotetan lactone, decarboxyl-cefotetan, and isomer cefotetan. Therefore, the method is rapid, sensitive and specific, and it is suitable for the identification of the impurities of cephalosporin.