Objective: To systematically characterize the impurity profile in Daptomycin raw material
by 2 Dimensional LC/MSn.
Methods: The target impurity was separated by first Dimensional HPLC and enriched by a 500μl loop,
then desalted using the on-line second Dimensional HPLC and analyzed by MS detector in positive
mode. Their structures were characterized based on the degradation mechanism and mass fragmentation
regularity of the cyclic lipopeptide, as well as the molecular thermodynamic calculation.
Results: A total of 12 impurities were characterized in the raw material, including 6 degradation products;
8 impurities are reported for the first time. The mass fragmentation regularities of 2 β-isomers of
Asp residue were summarized.
Conclusion: The structures of impurities in Daptomycin raw material, especially for β-isomer impurities,
could be rapidly identified by on-line 2 Dimensional LC/MSn method together with the molecular