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

Two-dimensional liquid chromatography with reversed phase in both dimensions: A review

Two-dimensional liquid chromatography (2D-LC), and in particular comprehensive two-dimensional liquid chromatography (LC×LC), offers increased peak capacity, resolution and selectivity compared to one-dimensional liquid chromatography. It is commonly accepted that the technique produces the best results when the separation mechanisms in the two dimensions are completely orthogonal; however, the use of similar separation mechanisms in both dimensions has been gaining popularity as it helps avoid difficulties related to mobile phase incompatibility and poor column efficiency. The remarkable advantages of using reversed phase in both dimensions (RPLC×RPLC) over other separation mechanisms made it a promising technique in the separation of complex samples. This review discusses some physical and practical considerations in method development for 2D-LC involving the use of RP in both dimensions. In addition, an extensive overview is presented of different applications that relied on RPLC×RPLC and 2D-LC with reversed phase column combinations to separate components of complex samples in different fields including food analysis, natural product analysis, environmental analysis, proteomics, lipidomics and metabolomics.

Characterization of Allergic Polymerized Impurities in Cephalosporins by MALDI-TOF MS/MS Spectrometry

Background:

Characterization of allergic polymerized impurities in cephalosporins is significant to ensure the safety and quality of the products.

Objective:

To develop a MALDI-TOF MS/MS method to characterize the structures of polymerized impurities in cefuroxime axetil drug substance and cefetamet pivoxil drug substance.

Methods:

Calibrant references were TOF mix, including Angiotensin 2, Angiotensin 1, Glu-1-fibrino, N-Acetyl renin, ACTH 1-17, ACTH 18-39 and ACTH 7-38. Matrix was DHB at a concentration of 10 mg•mL-1. Acetone and water were used as solvent to dissolve cefuroxime axetil and cefetamet pivoxil hydrochloride drug substances, respectively. The prepared solutions were mixed with DHB, volatilized to dry, and subjected to MALDI-TOF MS/MS analysis, respectively. MS data was obtained in the linear mode with a power of 80, and MS2 data was obtained in the reflection mode with a power of 120. Molecular weights of polymerized impurities in cefuroxime axetil and cefetamet pivoxil were obtained based on the MS data. Their fragmentation patterns and structural assignments were studied based on the MS2 data.

Results:

Eight polymerized impurities in cefuroxime axetil drug substance and cefetamet pivoxil hydrochloride drug substance made in China were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS/MS), among which impurity Ⅰ-Ⅴ were in cefuroxime axetil and impurities Ⅵ-Ⅷ were in cefetamet pivoxil. Based on the experimental results, the polymerization mechanism of polymerized impurities in cephalosporins was discussed.

Conclusion:

MALDI-TOF MS/MS was proved to be simple, quick and sensitive for the analysis of polymerized impurities in cephalosporins.