Radiocarbon content of synthetic and natural semi-volatile halogenated organic compounds

Some halogenated organic compounds, Such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polybrominated diphenyl ethers (PBDEs), have been suggested to have these compounds from their commercially synthesized counterparts is difficult. Molecular-level C-14 analysis may be beneficial since most synthetic compounds Lire manufactured from petrochemicals (C-14-free) and natural compounds should have "modern" or "contemporary" C-14 levels. As a baseline study, we measured, for the first time, the C-14 abundance in commercial PCB and PBDE Mixtures, a number of organochlorine pesticides, as well as one natural product 2-(3', 5'-dibromo-2'-methoxyphenoxy)-3,5-dibromoanisole. The latter compound was isolated from a marine sponge and is similar in structure to a PBDE. All of the synthetic compounds wore C-14-free except for the pesticide toxaphene, which had a modern C-14 abundance, as did the brominated natural compound. The result for toxaphene was not surprising Since it was commercially synthesized by the chlorination of camphene derived from pine trees. These results suggest that measuring the C-14 content of halogenated organic compounds may be quite useful in establishing whether organic compounds encountered in the environment have natural or synthetic origins (or both) provided that any synthetic counterparts derive from petrochemical feedstock. (C) 2002 Elsevier Science Ltd. All rights reserved.