We added known impurities in the starting materials to see if there were any new impurities that were being produced. Using a similar impurity deduplication step, as earlier, we found one new impurity that was being produced in R2 (Figure ). We observed no new impurities coming from reactions with trace metal impurities (Hg, As, Pb, Cd) in nitric acid (HNO 3 ), a single impurity from reactions with ammonia (NH 3 ), formaldehyde (HCHO), formic acid (HCOOH), carbon monoxide (CO), and carbon dioxide (CO 2 ) in hydrogen gas (H 2 ), and no new impurity formed by reaction with acetic acid (CH 3 COOH) impurity in acetic anhydride (Ac 2 O). The impurities in the specific reagents were obtained from the literature . In this example, no additional impurities, such as those arising from different work-up steps were added.