This normally involves isotope-ratio mass spectrometry. The precision of a dating method depends in part on the half-life of the radioactive isotope involved.For instance, carbon-14 has a half-life of 5,730 years.It is therefore essential to have as much information as possible about the material being dated and to check for possible signs of alteration.Precision is enhanced if measurements are taken on multiple samples from different locations of the rock body.
This predictability allows the relative abundances of related nuclides to be used as a clock to measure the time from the incorporation of the original nuclides into a material to the present.
Isotopic systems that have been exploited for radiometric dating have half-lives ranging from only about 10 years (e.g., tritium) to over 100 billion years (e.g., samarium-147).
For most radioactive nuclides, the half-life depends solely on nuclear properties and is essentially a constant.
The basic equation of radiometric dating requires that neither the parent nuclide nor the daughter product can enter or leave the material after its formation.
The possible confounding effects of contamination of parent and daughter isotopes have to be considered, as do the effects of any loss or gain of such isotopes since the sample was created.