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| Isotop ratio analyses |
| Lead, uranium and other elements |
Ratios are reported with appropriate standard deviations (absolute and relative).
Please contact the laboratory to discuss which elements are suitable for isotope analysis.
ISOTOPES
lsotopes are atoms of a specific element that have different masses. In nature, most elements occur as a mixture of several so-called stable isotopes in more or less constant proportions. For example, magnesium with masses 24, 25 and 26 amu (units of mass) in the proportions 79:10:11. Certain elements also occur as unstable (radioactive) isotopes.
QUANITITATIVE ANALYSIS
In analyses using ICP-MS, different isotopes of an element are always measured separately. The concentration can in principle be calculated from any one of the element's isotopes, which enhances the reliability of the analysis.
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ISOTOPE RATIOS
The quantitative relationship of isotopes (calculated by the number of atoms) is measured between pairs of isotopes for a given element. ALS has access to multicollector technology (MC-ICP-MS) that gives very high precision (down to approximately 0.001% relative standard deviation) in isotope ratio measurements. This allows for, i.a., geological dating. ICP-SFMS gives a certainty down to approximately 0.05%. This certainty is enough to separate Pb from different sources by its natural variation in isotope composition for, e.g., toxicological investigations.
TRACE ELEMENT STUDIES
Tracers are used for monitoring and charting chemical processes, mainly within biological and medical research. An element can be "marked" with an enriched stable isotope of that element for the purpose of studying its transformation and distribution in, e.g., organisms. The use of stable isotopes is preferred to the use of radioactive isotopes in these applications considering that they do not pose any radiation risks.
ISOTOPE DILUTION
Isotope dilution is a sophisticated method for quantitative analysis of elements. After "spiking" the sample with a stable enriched isotope of an element, the original concentration of that element can be calculated from the measured change in one or more isotope ratios. Isotope dilution has several advantages over conventional quantitative analyses and generally provides greater accuracy.
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