Analytical Methods:Isotopes

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Questions
Stable isotopes are non-radioactive, i.e. they do not decay over time. Many chemical elements have more than one isotope, including H, O, C, N, Sr and Pb. As the isotopes have slightly differing weights the relative frequency of the different isotopes can be affected by a range of geological, environmental and biological processes (kinetic fractionation). These differences have been exploited as a means of tracing soil inputs (Wilson et al., 2006), studying past land management practices (Fernandez et al., 2005; Simpson et al., 1999), and providing palaeoclimatic information.

Case studies where stable isotope analysis has been used in archaeology include:
 * Pb isotopes to trace soil inputs

Analysis
For isotope analysis careful sample preparation is required to isolate and concentrate the elements of interest. Sample preparation will usually be carried out by the laboratory responsible for analysis.

Mass spectrometers are used in isotopic analysis, in particular Isotope Ratio Mass Spectrometers are used (IRMS), but also Thermal Ionisation Mass Spectrometers (TIMS). Mass spectrometers use magnetic fields to separate ions according to their mass and electrical charge; this enables the identification of isotopes of elements which have the same charge but different mass.

Related techniques

 * Element concentration analysis
 * Multi-element concentration analysis
 * Radiogenic isotope analysis
 * Biomolecules

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