Isotopic abundance

Isotopic abundance is the relative proportion of each isotope of an element in a sample. It may be expressed as a fraction, percentage, or ratio.

Mass spectrometry: An analytical technique that separates ions by their mass-to-charge ratios and measures their abundance. Its mass-separated ion signals are used to estimate isotope proportions.
Isotope: One of two or more atoms of the same element with different numbers of neutrons. Abundance counts how much of each isotope occurs in a sample.
Radiometric dating: A method of determining age from the predictable decay of radioactive isotopes. Dating calculations depend on parent and daughter isotope proportions.
Isotopic signature: A characteristic pattern of isotope ratios associated with a material's source or history. It treats abundance patterns as identifying evidence rather than merely composition.
Isotope-ratio mass spectrometry: A mass-spectrometric technique designed to measure ratios between isotopes of an element precisely. It measures small differences in isotope ratios across samples.
Atomic number: The number of protons in an atomic nucleus, which determines an element's identity. Isotopes share this number while differing in neutron count.
Radiocarbon dating: A dating method that estimates the age of once-living material from its carbon-14 content. It compares carbon-14 abundance with stable carbon in a sample.
Isotope enrichment: A process that increases the proportion of a selected isotope in a material. Enrichment deliberately shifts proportions away from the starting composition.
Quadrupole mass analyzer: A mass analyzer that filters ions by mass-to-charge ratio using oscillating electric fields. It can distinguish isotope peaks by selecting ions with different mass-to-charge ratios.
Mass number: The total number of protons and neutrons in an atomic nucleus. Different mass numbers help distinguish isotopes in measured spectra.

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