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Stable Isotopic Analysis

Stable Isotopic Analysis. William Kou Jonathan Mertz. Limitations of Stable isotope ratio. Each sample can cost $200 - $400 for one sample, for one isotope ratio. Standards are precious and expensive The data varies from site to site

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Stable Isotopic Analysis

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  1. Stable Isotopic Analysis William Kou Jonathan Mertz

  2. Limitations of Stable isotope ratio • Each sample can cost $200 - $400 for one sample, for one isotope ratio. • Standards are precious and expensive • The data varies from site to site • If comparing two samples, the error associated with each sample must be outside the margin of the error of the second sample.

  3. Another problem with stable isotope analysis is that standardization proves to be difficult • The IAEA standard (International Atomic Energy Agency) is the primary standard which is used to calibrate the instrument in the laboratory, and is very expensive and hard to obtain. • Not many laboratories in the world that can do it. (only 4 in the U.S. as of 2008)

  4. Not as effective for compounds that are water soluble • There are two methods that can easily confound the analysis CSIR data: • Heterogeneity in flow paths • Proximity to other sources of contamination

  5. Site Sample variation • As stated in the article, “…has been criticized for being too costly, requiring greater interpretation, and being too variable from site to site.” • Sampling from site to site can be found to be inconsistent.

  6. In the uptake of a groundwater sample, contaminants are easily taken from an undesired area.

  7. Contaminant degradations along flow paths are not always the same.

  8. Proximity to other sources of Contamination • Sources of new contamination to ground water allow fresh (unfractionated) material to dissolve into water to replace the material that was removed by degradation • This dilutes the fractionated material and reduces the overall value of δ13C.

  9. Isotopic analysis works best for volatile compounds, but is not as reliable for water soluble compounds. • The detection limit for water soluble compounds increases by an order of magnitude or more.

  10. another option to measuring contaminants in Water samples • Spectrophotometers are cheap, fast, and extremely easy to use. • They are accurate in quantifying the amount of contaminant within a sample. • Most widely used around the world • Very little training required to operate

  11. Conclusion Stable Isotopic Analysis is an interesting technique requiring far more refinement. It is a costly and difficult process in which few laboratories in the world are capable of completing. The results also can vary from site to site. Cheaper and much more common alternatives are available such as Spectrophotometry.

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