Skip to main content

isotope dilution

isotope dilution An analytical technique used to determine the concentration of an element in a sample by means of a mass spectrometer. The method is based on the determination of the isotopic composition of the element in a mixture. A known quantity of a compound containing an unknown quantity of a particular element is mixed with a spike (a known weight of a radioactive isotope of the element). The specific activity (disintegrations per second per kilogram) of the spike is known precisely, so the isotopic composition of the mixture can be used to calculate the amount of the element in the sample. A small amount of the mixture is isolated from the sample, weighed, and its specific activity measured. The concentration of the inactive element in the sample may be estimated by the dilution of the radiotracer. Isotope dilution analysis can be applied to all elements that have two or more naturally occurring isotopes (about 80% of all elements), provided that a spike enriched in one of the isotopes of that element is available. As a technique it has several advantages over other analytical methods. It is free of interference from other elements present and its accuracy is governed by the calibration of the spike solution.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"isotope dilution." A Dictionary of Earth Sciences. . 16 Sep. 2019 <>.

"isotope dilution." A Dictionary of Earth Sciences. . (September 16, 2019).

"isotope dilution." A Dictionary of Earth Sciences. . Retrieved September 16, 2019 from

Learn more about citation styles

Citation styles gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA).

Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, cannot guarantee each citation it generates. Therefore, it’s best to use citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

Modern Language Association

The Chicago Manual of Style

American Psychological Association

  • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates.
  • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or works cited list.