Abstract:

In this work, the hyphenated liquid chromatography-diode array detector-solid phase extraction-nuclear magnetic resonance/mass spectrometry (LC-DAD-SPE-NMR/MS) technique is employed to characterize a novel degradation impurity with an approximate content of 0.3%~0.4% in cabazitaxel injection. In LC analysis, the impurity is co-eluted with tween-80, an important excipient contained in cabazitaxel injection, which poses a great challenge for high-purity degradation impurity isolation and further structure elucidation. Based on LC-DAD-SPE-NMR/MS hyphenation, automatic SPE is performed to trap and concentrate the impurity, and extensive NMR analysis was performed to characterize the structure of the impurity. In the ¹H NMR spectrum, partial peaks of the impurity are overlaid with co-eluted tween-80. To navigate the complexity, ¹H-¹H, ¹H-¹³C correlations, ¹H and ¹³C chemical shifts are extracted from the interfering peaks of tween-80 based on extensive analysis of 2D NMR spectra. Finally, the structure of the impurity is elucidated to be a cabazitaxel isomer with a rearranged taxane skeleton. The elucidation is completed in less than 48 h, showcasing a successful application of LC-DAD-SPE-NMR/MS hyphenation in determining the structure of an unknown trace impurity in pharmaceutical drugs, which evidences its capability and application prospects in the pharmaceutical industry.

Key words: cabazitaxel, degradation impurity, LC-DAD-SPE-NMR/MS, structure elucidation, analytical method