While our model obtained very low accuracy on our internal test set, analytical chemists were able to elucidate these structures. They could do so by leveraging a wide range of additional information that is known based on the expected main component, the chemical process used to synthesize it, and additional knowledge gathered over time by working on the project. All this information can suggest where the impurity differs from the main compound, and sometimes even in which way. In our experience, three quarters of the impurities considered in small molecule analytical development share between 50% and 80% of the molecular structure with the main compound. This common substructure provides a crucial starting point to allow analytical chemists to manually elucidate impurities from MS/MS spectra.