Britannica
Sources used in this answer
How does isotope dilution analysis measure a nonradioactive substance?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
chemical analysis
Strip of pH paper resting on specimen, with a comparison chart.
Isotope dilution analysis is a powerful analytical technique used to measure the quantity of a nonradioactive (stable) substance by utilizing its isotopic properties.12
The process works through the following steps:
- Addition of a Spike: A known, precisely measured quantity of an isotopically enriched version of the element—known as a spike—is added to the sample containing the unknown amount of the substance.23
- Mixing: The spike is thoroughly mixed with the original material. Because the spike and the natural element are chemically identical, they become indistinguishable during subsequent chemical processing.23
- Measurement: The mixture is analyzed, typically using mass spectrometry, to determine the ratio between the isotopes present in the spike and those naturally occurring in the sample.123
- Calculation: By knowing the exact amount of the spike added and the resulting isotopic ratio, the original quantity of the element can be calculated.23
A significant advantage of this method is that because the result depends on the ratio of isotopes, the loss of a portion of the sample during preparation does not affect the final accuracy.3