Apart from the a priori impurity prediction from proposed reaction schemes, a major part of chemical process development involves the identification of impurities after the experiments. The identification involves analysis of reaction characterization data, such as nuclear magnetic resonance (NMR) , liquid chromatographymass spectrometry (LC-MS) , and other analytical data streams. This post hoc analysis requires an intimate understanding of the specific analytical methods, thereby necessitating the involvement of subject matter experts from analytical chemistry, and other fields, to help in the elucidation of the impurity structures.