In 1946 American chemist Willard Libby predicted that there should be a significant difference in 14C activity between living organisms and fossil carbons due to the long half-life of 14C. In the following years, Libby and his team of researchers at the University of Chicago conducted a series of experiments testing this prediction and its implications. This research ultimately led to the publication of the first set of radiocarbon dates in 1949.

One of the greatest achievements of Libby and his team was that they devised a means of measuring the extremely low concentrations of 14C that are found in nature. Instead of counting 14C atoms directly, they used a Geiger-Müller counter to measure the radioactivity of solid carbon samples, inferring the concentration of 14C from the number of decay events over time, in counts per minute (cpm). Libby and his team measured the 14C activity of modern terrestrial organisms, and concluded that the concentration of 14C in living things was constant across time and space. Thus, it would be possible to calculate the 14C activity expected at a given time after the organic material was removed from the life cycle.

Libby and colleagues tested their method on known-age geological and archaeological materials. The first reported radiocarbon age was for a piece of wood taken from the tomb of Zoser, an Egyptian king who reigned from 2665 to 2650 BC. Radiocarbon age determinations from this and other historically dated Egyptian artifacts, as well as tree-ring dated wood samples – widely known as the “Curve of Knowns” – demonstrated “satisfactory” agreement between the expected and measured ages. Libby was awarded the Nobel Prize in Chemistry for his research on 14C dating in 1960.

Standard turnaround time is 3 weeks. Turnaround time for rush samples is 7 business days. Please call ahead for turnaround times for sample quantities exceeding 30, or for rush samples requiring a turnaround time shorter than 7 business days.

The reported 14C age is corrected for isotope fractionation based on δ13C measured by IRMS. The error is quoted as one standard deviation and reflects both statistical and experimental errors. Standard deviations for full-size samples are typically ± 20–25 14C yr (0.1–0.25 pMC) for samples younger than 5,000 14C yr.

To achieve greater precision, multiple measurements can be made on the same sample to calculate a weighted average and error. Additional fees are charged for this service, as it requires different portions of the same sample to be pretreated, graphitized, and measured independently.

We are happy to include calibrated calendar ages in your report. There is no charge for this service.