Looking at the periodic table of the elements, we see that more than 60 elements exhibit natural variations in their isotopic abundances. This variability arises either from nuclear processes, such as radiogenic ingrowth from a radioactive decay, or from stable isotope fractionation – a phenomenon in which isotopes of an element participate to different extents in physical or (bio)chemical processes due to their mass differences resulting in a discrimination of either the lighter or the heavier isotopes during the process. Although the relative variations in stable isotopic compositions (i.e., relative isotope abundances) are subtle – on the order of parts per ten thousand – they are significant, robust, and measurable using advanced analytical techniques such as multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS).

Isotopic signatures can provide valuable information about the composition and history of samples across various research fields, including geosciences, environmental sciences, life sciences, archaeometry, and nuclear forensics. Important applications include tracing sources and origins as well as studying natural processes. However, contamination, interferences, and instrumental isotopic fractionation present analytical challenges in determining isotopic signatures that, if unaddressed, can bias results and obscure systematic variations in samples.

This talk will provide an overview on the fundamentals of isotope ratio measurements and discuss the key challenges in achieving reliable and precise isotopic data, along with examples from the method development. Finally, the potential of isotopic analysis for studying metabolic processes will be illustrated with a recent case study.