The Story of Radiocarbon Dating

I recently shared a story that included radiocarbon dating.  By happy coincidence, December 17 is the birthday of Willard Libby, the American chemist who invented it.

The element carbon exists in several different isotope forms (carbon-12, carbon-13 and carbon-14), depending on the number of neutrons in its atom.  Carbon-14 is constantly being formed in the atmosphere as cosmic rays interact with nitrogen gas, and it gets absorbed by every living thing on Earth.  Because carbon-14 is mildly radioactive, it has a specific half-life (rate of decay).

When an organism dies, it stops absorbing carbon-14, which then begins to decay.  By measuring how much carbon-14 still remains in an organic compound, you can calculate how old it is.  This method also works on some inorganic compounds, as long as they also assimilated carbon-14 during their formation.

Libby confirmed the accuracy of radiocarbon dating by comparing his results with the known age of tree ring samples.  Libby’s 1947 announcement revolutionized our understanding of history, and he was awarded the 1960 Nobel Prize.

Radiocarbon dating is now a standard tool in archaeology.  Ironically, archaeological bones are among the most difficult objects to date accurately.  This is because bone is a composite material that includes both organics (mostly collagen) and minerals.  Bone is also porous, so fluids and microbes can penetrate and destroy the precious collagen over time.

This is where Agilent technologies come in.

German scientists conducted systematic research to identify optimal preservation criteria for bone mineral in archaeological bones.  They used an Agilent ICP-MS to obtain trace element concentration profiles on bone samples.

UK scientists investigated the most suitable techniques for extracting the highest-quality collagen from archaeological bones.  They used an Agilent Cary FTIR spectrometer and an Agilent ICP-MS system in their analysis of various extraction methods.

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