Light-stable isotopes, applications

Relative measurements are most commonly used to express small variations in the natural abundance of light stable isotopes and find applications in areas such as the geosciences and ecological research. No consensus exists on the appropriate units in which isotope ratios are reported, especially in the biomedical field. Most isotope ratio mass spectrometers (IRMS) report isotopic abundance in terms of delta notation ( parts per thousand or per mil ), which is a convention determined by geochemistry, because most of the original IRMS instruments were developed in isotope geochemistry laboratories. Delta units are not SI units. The SI base unit for quantity is the mole, from which atom fraction and mole fraction are derived. The units of stable isotope abundance, at.% and mol.%, are the atom and mole... 

The two primary applications of MS to biomolecular archaeology are the study of human diet and life histories using light stable isotopes and trace elements, and the analysis of residues on ceramics and other artifacts. 

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