About us

Group members as of October 2015

Environmental Organic Isotope Chemistry

Our research interest lies in the transformation of organic chemicals in the environment and in living organisms:

To address these scientific challenges, our group tailors a spectrum of traditional and innovative analytical methods. Besides gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem MS (LC-MS/MS), our focus lies on compound-specific isotope analysis (CSIA) at natural isotopic abundance (i.e., of 13C/12C, 15N/14N, 2H/1H, 37Cl/35Cl). We use isotopes as reactive tracers within organic molecules to


  • distinguish sources and trace fluxes of compounds that are chemically identical
  • demonstrate that a chemical is transformed in the environment. We make use of kinetic isotope effects: heavy isotopes (e.g., 13C, 15N, 2H or 37Cl) become enriched when chemicals are transformed. This enrichment gives proof of their degradation, even if metabolites cannot be detected
  • elucidate underlying (bio)chemical reaction mechanisms and degradation pathways. Isotope effects of multiple elements can constrain underlying transition states and, therefore, elucidate different transformation pathways from isotope data alone

Such complementary information provides a new angle to elucidate transformation of organic pollutants in natural and engineered systems.


M. Elsner, M. A. Jochmann, T. B. Hofstetter, D. Hunkeler, A. Bernstein, T. C. Schmidt, A. Schimmelmann, Current challenges in compound-specific stable isotope analysis of environmental organic contaminants, Analytical and Bioanalytical Chemistry, 403 (2012), 2471–2491.

M. Elsner, Stable Isotope Fractionation to Investigate Natural Transformation Mechanisms of Organic Contaminants: Principles, Prospects and Limitations, Journal of Environmental Monitoring, 12 (2010), 2005-2031