Mass spectrometry for stable isotope ratios of heavy elements

Isotope Ratio Mass Spectrometry (IRMS) is a specialized technique used to provide information about the geographic origins of inorganic substances. The ability to determine the source of an inorganic substance stems from the relative isotopic abundances of the elements which comprise the material. Because elements such as lead, strontium, and osmium have so-called radiogenic isotopes, certain isotope ratios of theses elements vary in nature. This varaiation can be used to differentiate between natural occurrences of these elements, even if they occur only in trace amounts. Thus, lead, silver, and copper deposits can be differentiated by lead isotope ratios, iron ore deposits by osmium isotope ratios and certain geagraphical regions by their strontium isotope ratios. Recently it has been found that there are also natural variations in the elements copper and silver, which can be used for provenance analysis of metals and pigments. These isotope ratios can be measured with multi-collector ICP mass spectrometers.