Study of the impurity profile and characteristic fragmentation of Δ3 -isomers in cephapirin sodium using dual liquid chromatography coupled with ion trap/time-of-flight 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.

Separation and characterization of two series of unknown degradation impurities caused by light irradiation and autoclaving in xinfujunsu injection using liquid chromatography tandem mass spectrometry

RATIONALE

A series of photodegradation impurities and a series of degradation impurities produced in autoclaving in xinfujunsu injection were discovered, and these unknown impurities were separated and characterized thoroughly using liquid chromatography tandem quadrupole time-of-flight mass spectrometry.

METHODS

The column was a Platisil 5 μm ODS (4.6 × 250 mm, 5 μm). For the analysis of degradation impurities caused by light irradiation and autoclaving, the mobile phase was composed of 0.01 M ammonium formate aqueous solution and acetonitrile/isopropanol (90:10, V/V). Full scan LC-MS and LC-MS² was carried out to obtain as much structural information as possible. The fragmentation behavior of actinomycin D, actinomycin S₃ , and its impurities was studied and used to obtain information about the structures of these impurities.

RESULTS

Based on MS² spectral data and exact mass measurements, the chemical structures of two series of degradation impurities were characterized, among which five unknown impurities were photodegradation impurities and seven unknown impurities were degradation impurities produced in autoclaving of xinfujunsu injection.

CONCLUSIONS

Based on characterization of impurities, this study also revealed the cause of impurity production and provided guidance for enterprises to improve the process and drug packaging material to reduce impurity content. Furthermore, this study also provided scientific basis for further improvement of official monographs in pharmacopoeias.

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

RATIONALE

The structural identification of impurities in cephalosporins has been reported. However, to the best of our knowledge, there was no report on the impurities of cefsulodin sodium, which is necessary for the quality control. Thus, the aim of this study was to separate and characterize the impurities in cefsulodin sodium raw material using liquid chromatography/tandem mass spectrometry (LC/MS/MS).

METHODS

The analytes were separated on a Kromasil 100-5C18 column (4.6 mm × 250 mm, 5 μm) using a gradient elution with a mobile phase consisting of 1% ammonium sulphate aqueous solution and acetonitrile in the first dimension. The separation in the second dimension was carried on a Shimadzu Shim-pack GISS C18 column (50 mm × 2.1 mm, 1.9 μm) with a mobile phase consisting of 10 mM ammonium formate solution and methanol.

RESULTS

The fragmentation behaviors of cefsulodin and its impurities were studied and the structures of the impurities were deduced based on the MSⁿ data. The structures of ten unknown impurities were proposed based on the work carried out in this study. The degradation behaviors of cefsulodin sodium were also studied. This revealed that cefsulodin sodium should be stored in a dry, cool and dark closed container.

CONCLUSIONS

Based on the characterization of impurities, this study not only revealed the mechanism by which impurities were produced, thus providing guidance to pharmaceutical companies for manufacturing process improvement and impurity control, but also provided a scientific basis for further improvement of official monographs in pharmacopoeias.