Geochemistry isotope ratio measurements

Applications of Isotope Ratio Measurements in Geochemistry and Geochronology... 

Quantitative analysis Inorganic MS can determine elements at ppt concentrations or below. Inorganic MS is used for simultaneous multielement analysis for metals and nonmetals. Inorganic MS provides the isotope distribution of the elements. Special mass spectrometers are used for accurate isotope ratio measurements used in geology and geochemistry. 

Shortly after the development of the early mass spectrometers, Li isotopes were identified by Francis Aston (1932). Although mass spectrometric techniques are those most commonly applied to the measurement of isotope ratios in geochemistry, attempts to quantify Li isotopes have been made using non-mass based emission methods (e.g., atomic absorption Zaidel and Korennoi 1961 various nuclear methods Kaplan and Wilzbach 1954 Brown et al. 1978 ... 

Equation (5.7), rather than (5.6), is used in isotope geochemistry, because mass spectrometers can measure isotopic ratios (G/Gg) significantly more precise than the amount of an isotope (G). 

In isotope geochemistry, ( Th/ U) reflects U-Th disequilibrium. This ratio is not measured directly from mass spectrometers. In stead, isotope composition measurement provides nd isotope dilution... 

The highly precise measurement of isotope ratios has a long tradition in organic geochemistry. Nowadays, the elucidation of stable isotope distributions is highly desirable in view of fundamental studies in biochemistry, nutrition, drug research and also in the authenticity assessment of food ingredients. 

So far, the only available technique capable of sufficiently accurate measurement of lead isotope compositions, both for isotope geochemistry and for archaeological applications, is thermal ionization mass spectrometry. Any well-equipped laboratory can routinely measure lead isotope ratios with... 

Isotope laboratories use different reference gases or working standards for the measurement of relative isotope ratios by mass spectrometry. However, all results are reported relative to an internationally accepted standard (Table 10.1). The selection of standards is an important procedure in isotope geochemistry because their definition and availability controls the extent to which results from different laboratories can be compared. 

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