Details

Autor(en) / Beteiligte

• Reddy, Christopher M
• Xu, Li
• O'Neil, Gregory W
• Nelson, Robert K
• Eglinton, Timothy I
• Faulkner, D. John
• Norstrom, Ross
• Ross, Peter S
• Tittlemier, Sheryl A

Titel

Radiocarbon Evidence for a Naturally Produced, Bioaccumulating Halogenated Organic Compound

Ist Teil von

• Environmental science & technology, 2004-04, Vol.38 (7), p.1992-1997

Ort / Verlag

Washington, DC: American Chemical Society

Erscheinungsjahr

2004

Quelle

MEDLINE

Beschreibungen/Notizen

• Halogenated organic compounds (HOCs) such as 1,1‘-dimethyl-3,3‘,4,4‘-tetrabromo-5,5‘-dichloro-2,2‘-bipyrrole (DBP-Br4Cl2) and heptachloro-1‘-methyl-1,2‘-bipyrrole (Q1) have been detected worldwide, sometimes at high levels in Antarctic air, seabird eggs, the blubber of marine mammals, and, most notably, even human milk. To date, it has been difficult to determine whether these compounds are natural products or derived from industrial synthesis. Molecular-level 14C analysis of these compounds is particularly appealing because most industrial compounds are manufactured from petrochemicals (14C-free) and natural compounds should have “modern” or “contemporary” 14C levels. To investigate the source of DBP-Br4Cl2, we isolated 600 μg of this compound (150 μg of carbon) from marine animal extracts by employing gel permeation chromatography, Florisil column chromatography, and two-dimensional preparative capillary gas chromatography. The purified DBP-Br4Cl2 was split into two samples (75 μg of carbon each) and analyzed by accelerator mass spectrometry for 14C content. The Δ14C values were −449‰ and −467‰, corresponding to conventional 14C ages of 4740 and 5000 years before present (BP), respectively. The presence of detectable 14C in the DBP-Br4Cl2 strongly points to at least a natural or biogenic source. However, these Δ14C values for DBP-Br4Cl2 are more depleted than expected for a recently synthesized natural product. Several explanations are discussed, but additional samples from discrete locations need to be analyzed before a clear understanding of the source (or sources) of this compound (and other unknown HOCs) is fully determined.