Experimental and Density Functional Theory Characteristics of Ibrutinib, a Bruton’s Kinase Inhibitor Approved for Leukemia Treatment

Figure 5

Ibrutinib’s tandem mass spectrum with a direct fusion of methanol solution using a high-resolution electrospray ionization mass spectrometer at a collision energy of 25 Joule. Two fragments were found at m/z = 304.1178 and 138.1123, corresponding to the pyrazole pyridine bond breakage.