Tandem mass spectrometry of small-molecule signal transduction inhibitors: Accurate-m/z data to adapt structure proposals of product ions

•Protein kinases inhibitors are important in the treatment of various cancers.•Therapeutic drug monitoring using liquid chromatography–tandem mass spectrometry is often performed.•Structures proposed in literature for product ions used in SRM are not always in agreement with accurate-m/z data.•Alternative structures are proposed for a number of these product ions.