The Organic Isotopologue Frontier

Organic molecules are key components of the Earth-life system. Their stable isotope composition provides information on various problems such as past climate, energy resources, or the synthesis of prebiotically relevant molecules on Earth and elsewhere. Organic molecules are made of isotopologues, molecules differing in the number and/or position of isotope substitution. Recent years have witnessed a boom in technological development dedicated to isotopologue measurement, leading to an unprecedented degree of information regarding organic (bio)synthesis. While applications in Earth and planetary sciences has been limited so far to simple hydrocarbons, typically methane, isotopologue proxies are expected to rapidly emerge in biogeochemistry, providing new types of environmental and biological tracers. This review describes principles and measurement techniques, as well as present and potential biogeochemical applications. ▪ Stable isotopes of organic molecules are widely used in biogeo-chemistry. ▪ Isotope analysis at the intramolecular level is expected to provide new information on the origin of molecules. ▪ Recent technological developments unlocked the potential of intramolecular isotope analysis, providing new proxies in biogeochemistry and new opportunities to clarify questions related to Earth and planetary sciences.