(R)-1-(3-(4-amino-3-(4-phenoxy-d5-phenyl)-1H-pyrazolo[3,4-d]pyrimidin-1-yl)piperidin-1-yl)prop-2-en-1-one acetate,(R)-1-(3-(4-amino-3-(4-phenoxy-d5-phenyl)-1H-pyrazolo[3,4-d]pyrimidin-1-yl)piperidin-1-yl)prop-2-en-1-one acetate,"Labeled Ibrutinib, intended for use as an internal standard for the quantification of Ibrutinib by GC- or LC-mass spectrometry.",Ibrutinib Therapeutic