Separation and structural elucidation of cefsulodin and its impurities in both positive and negative ion mode in cefsulodin sodium bulk material using liquid chromatography/tandem mass spectrometry

Abstract

The structure identification of impurities in cephalosporins was reported. However, to the best of our knowledge, there was no report on impurities of cefsulodin sodium, which is necessary for the quality control. Thus, the aim of this study was to separate and characterize the impurities in cefsulodin sodium raw material using LC-MS/MS. The analytes were separated on a Kromasil 100-5C18 column (4.6 mm ×250 mm, 5 μm) by a gradient elution with a mobile phase consisting of 1% ammonium sulphate aqueous solution and acetonitrile in the first dimension. The separation in the second dimension was carried on a Shimadzu Shim-pack GISS C18 column (50 mm × 2.1 mm, 1.9 μm) with a mobile phase consisting of 10 mM ammonium formate solution and methanol. The fragmentation behaviors of cefsulodin and its impurities were studied and the structures of impurities were deduced based on the MSn data. The structures of ten unknown impurities were proposed based on the work carried out in this study. The degradation behaviors of cefsulodin sodium were also studied. It revealed that the storage environment of cefsulodin sodium should be preserved in a dry, cool and dark closed container. Based on the characterization of impurities, this study not only revealed the mechanism of impurity production, thus providing guidance to pharmaceutical companies for manufacturing process improvement and impurity control, but also provided a scientific basis for further improvement of official monographs in pharmacopoeias.