Study of the polymerized impurities in cefotaxime sodium and cefepime by applying various chromatographic modes coupled with ion trap/time-of-flight mass spectrometry

Abstract

Polymerized impurities in β-lactam antibiotics can induce allergic reaction, which seriously threaten the health of patients. In order to study the polymerized impurities in cefotaxime sodium and cefepime, a HPSEC method with TSK-gel G2000SWxl column and a RP-HPLC method with C18 column were established to replace the classical gel filtration chromatography with Sephadex G-10 gel as stationary phase. Two-dimensional (2D) liquid chromatography was employed to further investigate the HPSEC and RP-HPLC method and ion trap/time-of-flight mass spectrometry was applied to characterize the structures of polymerized impurities eluted from the two methods. The structures of the polymerized impurities in cefotaxime sodium and cefepime were deduced based on the MSⁿ data, six of which were previously unknown. The corresponding relationship of impurities between the two methods was established, and the specificity of the two methods was compared. The results showed that the polymerized impurities in cefotaxime sodium and cefepime were co-eluted with other small molecular weight impurities with high polarity in HPSEC, leading to a poor specificity. The newly established RP-HPLC methods could effectively separate and detect polymerized impurities and were suitable for the quality control in daily analysis.

Keywords: 2D LC-IT/TOF MS; Cefepime; Cefotaxime sodium; HPSEC; Polymerized impurity; RP-HPLC.