import error when updating - The fractionation technique dating
Fractionation also describes variations in the isotopic ratios of carbon brought about by non-natural causes.For example, samples may be fractionated in the laboratory through a variety of means; incomplete conversion of the sample from one stage to another or from one part of the laboratory to another.
It is common practice in Carbon-14 laboratories to correct radiocarbon activities for sample fractionation.
The resultant ages are termed “normalized”, meaning the measured activity is modified with respect to -25 o/oo (per mille) with respect to VPBD.
Some processes, such as photosynthesis for instance, favors one isotope over another, so after photosynthesis, the isotope C13 is depleted by 1.8% in comparison to its natural ratios in the atmosphere (Harkness, 1979).
Conversely the inorganic carbon dissolved in the oceans is generally 0.7% enriched in 13C relative to atmospheric carbon dioxide.
Isotopic fractionation of stable carbon isotopes Carbon-13 (13C) and Carbon-12 (12C) involves alterations in the ratios of isotopic species as a function of their atomic mass as a result of natural biochemical processes.