Stable isotopes are atoms of the same element that differ in mass. The ratio of stable carbon, nitrogen, oxygen, or hydrogen isotopes in organic material, water, or the atmosphere can vary and contain important environmental or biological information. This is because stable isotope ratios of carbon, nitrogen, oxygen, or hydrogen in plant and animal tissue, in water, or the atmosphere can:

• indicate processes
• integrate processes
• record processes
• trace the origin of substances

With this, the analysis of stable isotopes has developed in the past decades into one of the most powerful tools in ecology, earth system sciences, and forensics.

In our laboratory at the University of Basel stable isotopes are analyzed using isotope ratio mass spectrometers (IRMS). The IRMS are coupled to different peripherals which allow the analyses of different sample types. We currently operate four IRMS to analyze:

• Carbon and nitrogen isotope ratios in solid materials (EA-IRMS)
• Hydrogen and oxygen isotope ratios in solid materials (TC/EA-IRMS)
• Hydrogen and oxygen isotope ratios in water (TC/EA-IRMS)
• Hydrogen isotope ratios in individual organic compounds (GC-IRMS)