Résumé
Research on polymer impurities has always been important in the quality control of cephalosporins. Research on polymers in cephalosporins that lack active amino groups on the C-7 side chain has not been reported. Therefore, our study used cefazolin sodium, which is widely used in the clinic, as an example. The polymer in cefazolin sodium and its product "cefazolin sodium pentahydrate for injection" was analyzed by column switching liquid chromatography-high resolution mass spectrometry. Two polymer impurity peaks were detected and the possible structures of these polymers were suggested. Through two-dimensional liquid chromatography, the chromatographic peaks following Sephadex gel chromatography and high-performance gel chromatography were compared to those obtained by reverse high-performance liquid chromatography (HPLC) for cefazolin sodium as reported in the Chinese Pharmacopoeia. The HPLC method proves more suitable for polymer detection than Sephadex gel chromatography and high-performance gel chromatography. The method of polymer detection for cefazolin sodium was established using the method of related substances HPLC as described in the Chinese Pharmacopoeia.
Résumé
OBJECTIVE: To establish a method for the separation and characterization of polymer impurities in azlocillin sodium for injection, and evaluate the efficacy of high performance gel filtration chromatography(HPGFC) method for determination of the polymer impurities. METHODS: Using two-dimensional HPGFC and reversed-phase liquid chromatography(RPLC)-mass spectrometer, an Ultimate SEC-120 column was used in the first dimensional chromatography, with isocratic elution using 5 mmol·L-1 phosphate buffer (pH 7.0) as the mobile phase. An XBridge C18 column was used in the second dimensional chromatography, with gradient elution using 10 mmol·L-1ammonium formate solution(pH 6.5) and 8 mmol·L-1ammonium formate in mixture of acetonitrile and water (200∶50) as the mobile phase. Two mass spectrometers with ESI source were used for 2D-LC-MSn. RESULTS: The polymer impurities found by HPGFC also included penicillenic acid of azlocillin and decarboxylated penicillenic acid of azlocillin. The chemical structures of four polymer impurities identified in the second dimensional RPLC were elucidated. CONCLUSION: The 2D-HPGFC-RPLC-MS method can be used to profile the polymer impurities in azlocillin sodium for injection, which is helpful to realize effective control over polymer impurities in β-lactam antibiotics.
Résumé
OBJECTIVE: To validate the conventional gel filtration chromatography (GFC) method for determination of the polymer impurities in β-lactam antibiotics and achieve combination of GFC and RP-HPLC system. METHODS: The effectiveness of the conventional GFC method was identified by 2D-GFC X LC-TOFMS and the polymer impurities found by GFC were identified by RPHPLC. RESULTS: The polymer impurities found by GFC mainly were degradation impurities and open β-lactam ring impurities, which could not effectively characterize the sensitizing polymer impurities in cefotiam hydrochloride. CONCLUSION: An effective method to characterize the polymer impurities in β-lactam antibiotics may be established on the basis of online column switching technique which effectively combines the advantages of GFC and the ability of RP-HPLC to identify the special impurities.