Correcting for Contamination in Ams 14c Dating

When using accelerator mass spectrometry (AMS) for radiocarbon dating, it is important to correct for carbon contamination that is added to the sample and the standard during chemical processing. We derive an equation for making this correction that generalizes previous work in several ways. We treat the case in which contaminating carbon is added during both the combustion step and graphitization step. Taking this two-stage contamination process into account is particularly important when only a fraction of the CO2 produced in the combustion is graphitized. We also allow for the fact that the 13C fractions of the sample, the standard, and the contaminants may be different.