Radiometric dating has been used to determine the ages of the Earth, Moon, meteorites, ages of fossils, including early man, timing of glaciations, ages of mineral deposits, recurrence rates of earthquakes and volcanic eruptions, the history of reversals of Earth's magnetic field, and many of other geological events and processes.
ASTM D6866 is the standard test method developed by ASTM International (formerly the American Society for Testing and Materials) to determine the biobased carbon/biogenic carbon content of solid, liquid, and gaseous samples using radiocarbon analysis.
The ratio is reported as a percentage with the units “p MC” (percent modern carbon).
If the material being analyzed is a mixture of present-day radiocarbon and fossil carbon (which contains no radiocarbon), then the p MC value obtained correlates directly to the amount of bio-diesel present in the sample.
The content of this isotope in the dead remains or fossils gradually decreases up to the point where there is essentially none left, taking approximately fifty thousand years.
Radiocarbon dating procedures accurately measure the carbon 14 content in various materials, and from carbon dating results one can calculate when the plant or animal died.
Because it can be used to analyze any type of sample, it is recognized to be a very good analytical method for different types of biofuel. Several versions have been published since then – ASTM D6866-04, ASTM D6866-04a, ASTM D6866-05, ASTM D6866-06, ASTM D6866-06a, ASTM D6866-08, ASTM D6866-10, ASTM D6866-11, ASTM D6866-12 and ASTM D6866-16.
ASTM D6866-18 is the current active version of the standard as of March 2018.Combining fossil carbon with present-day carbon into a material will result in a dilution of the present-day p MC content.By presuming 105 p MC represents present-day bio-diesel materials and 0 p MC represents petroleum derivatives, the measured p MC value for that material will reflect the proportions of the two component types.When living things die, they stop taking in carbon-14, and the radioactive clock is "set"!Any dead material incorporated with sedimentary deposits is a possible candidate for carbon-14 dating.One can interpret the reported percentages as maximum values (the most conservative interpretation).