Abstract
Twenty-four samples of CO2 from combustion of the NBS oxalic-acid radiocarbon standard, submitted from 13 radiocarbon laboratories, were analyzed for C13 content in this laboratory in order to provide comparative data for normalizing the counting results. The samples were analyzed on Samson, a 60° sector, six-inch radius, McKinney-Nier type mass-spectrometer with magnetic switching between sample and standard gas feed to the instrument.