Radiocarbon analyses were used to determine the "biobased content" of a variety of diverse samples. The theoretical biobased contents of those samples were compared to the biobased content values obtained by radiocarbon analyses. Results of this work indicated that the radiocarbon analyses provided accurate (within +/- 3%, absolute) biobased content values for the samples tested. It is not practical to examine the accuracy of the radiocarbon analyses for every possible type of sample matrix. However, based on analyses performed on various types of samples, every indication is that the analyses provide accurate and reliable results on the biobased content of liquid and solid materials. (c) 2006 Elsevier Ltd. All rights reserved.