Radioactive age dating for organic matter
The radiocarbon age of a certain sample of unknown age can be determined by measuring its carbon 14 content and comparing the result to the carbon 14 activity in modern and background samples.
The principal modern standard used by radiocarbon dating labs was the Oxalic Acid I obtained from the National Institute of Standards and Technology in Maryland. Around 95% of the radiocarbon activity of Oxalic Acid I is equal to the measured radiocarbon activity of the absolute radiocarbon standard—a wood in 1890 unaffected by fossil fuel effects.
Radiocarbon dating is essentially a method designed to measure residual radioactivity.An age could be estimated by measuring the amount of carbon-14 present in the sample and comparing this against an internationally used reference standard.