Isotope dilution

The isotope dilution analysis ( IVA ) is a technique for trace and ultra- trace analysis. Until the early 1990s, it was mainly considered for geological questions to rate, but later she moved as a routine use to the analytical laboratories.

Most elements have a natural isotope distribution, which is the same for natural occurrence of the elements in all the earth. When analyzing a sample by IVA an isotope standard is added with non-natural, but known isotopic distribution. Thereby, the isotope distribution is modified in the sample. After determination of the isotopic distribution using a mass selective detector, the original isotopic distribution can then be determined.

The isotopic distribution of RM can be calculated using the following formula:

Conditions for the IVA are:

  • The element to be determined must have isotopes that are durable enough;
  • It is necessary to work with a mass selective detector;
  • Add the given standard must be consistent with the sample in chemical equilibrium.

Advantages of this technique:

  • After addition of the standards, a loss of substance does not distort the analysis result;
  • It is a single-point calibration possible;
  • The consumption of materials is extremely low;
  • At the IVA is an absolute method;
  • It is highly accurate.

Cons:

  • Not every element has a stable ( long-lived ) isotopes;
  • Mass-selective detectors are usually expensive;
  • Isotopically labeled standard compounds are also expensive or complicated to synthesize;
  • Reaching the chemical balance is not possible with each of the sample matrix.
  • Chemical analysis methods
Chemical element Integrated Authority File
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