Radiocarbon dating can only be made on organic materials
One of the nice things about this method is that we don't have to worry about carbon being lost from the sample.
Because we are measuring the abundance of two isotopes of carbon, and because isotopes of the same element will be chemically identical, no ordinary process can preferentially remove C is going to be small enough to begin with, being only 0.0000000001% of atmospheric carbon, and then as the decay process progresses it's going to get smaller and smaller.
There are three carbon isotopes that occur as part of the Earth's natural processes; these are carbon-12, carbon-13 and carbon-14.
The unstable nature of carbon 14 (with a precise half-life that makes it easy to measure) means it is ideal as an absolute dating method.
So even we humans are radioactive because of trace amounts of radiocarbon in our bodies.
Radioactive and non-radioactive carbon dioxide mix throughout the atmosphere, and dissolve in the oceans.It also has some applications in geology; its importance in dating organic materials cannot be underestimated enough.In 1979, Desmond Clark said of the method “we would still be foundering in a sea of imprecisions sometime bred of inspired guesswork but more often of imaginative speculation” (3).Plants and animals naturally incorporate both the abundant C-12 isotope and the much rarer radiocarbon isotope into their tissues in about the same proportions as the two occur in the atmosphere during their lifetimes.When a creature dies, it ceases to consume more radiocarbon while the C-14 already in its body continues to decay back into nitrogen.