SEPARATION AND CHARACTERIZATION OF THE IMPURITIES AND ISOMERS IN CEFMENOXIME HYDROCHLORIDE BY HPLC-UV-MSⁿ

Abstract

The twelve impurities and isomers in cefmenoxime hydrochloride were separated and identified by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MSⁿ). A discipline of mass fragmentation pattern and structure for the E-isomer and Δ³-isomer of oxime cephalosporin antibiotics was presented to distinguish their structures. The column was Alltima C₁₈(250 × 4.6 mm, 5 µm). The mobile phase was water-acetic acid-acetonitrile (85:1:15). In positive mode, full scan LC-MS was first performed in order to obtain the m/z value of the protonated molecules of all detected peaks. LC-MS-MS and LC-MS-MS-MS were then carried out on the compounds of interest. The complete fragmentation patterns of twelve impurities were studied and used to obtain information about the structure of these impurities. The relationship of mass fragmentation pattern and structure for cefmenoxime, E-isomer of cefmenoxime and Δ³-isomer of cefmenoxime was studied. The structures of the twelve impurities and isomers in cefmenoxime hydrochloride were deduced based on the HPLC-MSⁿ data, assisted by the UV spectra and stress testing.

Keywords:

• cefmenoxime hydrochloride
• HPLC-ESI-MSⁿ
• identification
• impurity
• isomer
• structure

Notes

Note: –, meant that the impurity content had no change.

+, meant that the impurity content increased.

+ +, meant that the impurity content increased obviously.