Résumé
Objective To establish a high performance size esclusion chromatography (HPSEC) method for the determination of high molecular weight impurities of cefotiam hydrochloride for injection.Methods A TSK G2000 SWXL column(7.8 mm × 30 cm,5μm) was used,the mobile phase consisting of phosphate budder solution [0.1 mol·L-1 disodium hyrogen phosphate-0.1 mol·L-1 sodium dihydrogen phosphate (61:39)],the flow rate was 0.7 mL· min-1,the detection wavelength was 254 nm,the column temperature was 30 ℃,the injection volume was 20 μL,and the concentration of polymers was quantified by external standard method.Results For HPSEC method,the calibration curves were linear in the range of 5.0-25.0 μg·mL-1 for cefotiam,and the LOD and LOQ was 0.1 μg·mL-1 and 0.246 μg· mL-1,the RSD for replicate for injections of reference solution was 0.50％,the sample solution was not stable in room temperature.Conclusion The method has high separation efficiency and good specificity,which provides reference for the further study of the polymer of cefotiam hydrochloride for injection.
Résumé
Reversed-phase liquid chromatography coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS) was used to characterize impurities in cefpodoxime proxetil, an ester-modified prodrug. Based on the mechanisms by which cephalosporins are degraded, stress tests were designed and performed. The bulk material and capsule were eluted through a C18 column with formic acid-methanol-water as the mobile phase. In total, 15 impurities were characterized in commercial samples, including 7 known impurities and 8 new impurities. The structures of these unknown compounds were deduced via comparison with the fragmentation patterns of cefpodoxime proxetil. Data from this systematic study will help improve the safety and quality of cefpodoxime proxetil.