Global Tracking of Transformation Products of Environmental Contaminants by 2 H-Labeled Stable Isotope-Assisted Metabolomics.

Stable isotope-assisted metabolomics (SIAM) enables global tracking of isotopic labels in nontargeted metabolomics in living organisms. However, its application in tracking transformation products (TPs, as metabolites of contaminants) of environmental contaminants is still a challenge due to limits in methodology, unmatured algorithms, and the high cost of 13 C-labeled contaminants. Therefore, we developed a 2 H-SIAM pipeline coupled with a highly flexible algorithm 2 H-SIAM(1.0) (https://github.com/kechen1984/2H-SIAM), facilitating tracking TPs of contaminants in the environmental matrix. A detailed discussion illustrates the theory, behavior, and prospect of 2 H-SIAM. We demonstrate that the proposed 2 H-SIAM pipeline has unique advantages over 13 C-SIAM, for example, cost-effective 2 H-labeled contaminants, easy synthesis of 2 H-labeled emerging contaminants, and providing more structural information. A pyrene soil degradation study further confirmed its high performance. It efficiently discarded 99% of noise signals and extracted 52 features from the nontargeted high resolution mass spectrometry (HRMS) data. Among them, 13 features were annotated as TPs of pyrene with identification confidence from Level 2a to Level 5, and 5 TPs were reported for the first time. In conclusion, the proposed 2 H-SIAM pipeline is powerful in tracking potential TPs of environmental contaminants with unique advantages.