From about untilwhen atmospheric nuclear testing was banned, it is estimated that several tonnes of 14 C were created. These treatments can damage the structural integrity of the sample and remove significant volumes of material, so the exact treatment decided on will depend on the sample size and the amount of carbon needed for the chosen measurement technique. After a final acid wash, the collagen is dried and measured for d13C. For example, rivers that pass over limestonewhich is mostly composed of calcium carbonatewill acquire carbonate ions. The study of tree rings led to the first such sequence: This information has also helped determine the age of the Earth itself. Carbon is distributed throughout the atmosphere, the biosphere, and the oceans; these are referred to collectively as the carbon exchange reservoir,  and each component is also referred to individually as a carbon exchange reservoir.
Once contamination has been removed, samples must be converted to a form suitable for the measuring technology to be used.
How Do Scientists Determine the Age of Dinosaur Bones?
After a final acid wash, the collagen is dried and measured for d13C. This allowed Libby to determine how much of the sample was ash, and hence to determine the purity of the carbon sample to be tested. It is possible to detect if there has been any degradation of the sample by comparing the relative volume of each amino acid with the known profile for bone. Related forms are sometimes used: During its life, a plant or animal is in equilibrium with its surroundings by exchanging carbon either with the atmosphere, or through its diet. The time-width of any given sample reflects the total growth of the original organism and the span of time that organism interacted with the biosphere. The results from AMS testing are in the form of ratios of 12 C13 Cand 14 Cwhich are used to calculate Fm, the "fraction modern".