Fragmentation behaviors of taxanes drugs using electrospray ionization with quadrupole time-of-flight mass spectrometry

The fragmentation pathways of two taxanes drugs have been studied in positive ion mode by Q-TOF with the advantages of high mass accuracy and high resolution analysis. The M+H⁺ ions were observed by ESI-MS, from which the molecular weights were obtained. Using the protonated pseudo-molecular ions M+H⁺ as internal reference compounds, the accurate mass and element composition of the fragment ions were determined. The collision induced dissociation (CID) data of the M+H⁺ ions provided fragmentation pathways of related compounds. Results showed that the major cleavage pathways of paclitaxel and docetaxel were the same that the cleavage of C-O bond between the side chain and taxol skeleton easily occurred, then stripping of the functional groups on the parent ring. Some common fragments were formed, such as m/z 105.033 7, 291.137 3, 309.148 5, 327.159 7, 387.181 2 and 509.217 4, which would provide a basis for future qualitative and quantitative analysis of taxanes in vitro and in vivo.