Environ. Sci. Technol. 2005, 39, 8684-8690
Identification, Quantification, and Synthesis of a Novel Dimethoxylated Polybrominated Biphenyl in Marine Mammals Caught Off the Coast of Japan GO ¨ R A N M A R S H , * ,†,‡ MARIA ATHANASIADOU,† IOANNIS ATHANASSIADIS,† ÅKE BERGMAN,† TETSUYA ENDO,§ AND KOICHI HARAGUCHI| Department of Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Hokkaido 016-0293, Japan, and Daiichi College of Pharmaceutical Sciences, Fukuoka 815-8511, Japan
Bioaccumulation of persistent organic compounds can eventually lead to concentrations in wildlife and humans that are deleterious to health. The present paper documents the identification, quantification, and synthesis of a novel compound, 2,2′-dimethoxy-3,3′,5,5′-tetrabromobiphenyl (2,2′diMeO-BB80), present in the marine mammals Striped dolphin (Stenella coeruleoalba), Bottlenose dolphin (Tursiops truncatus), Minke whale (Balaenoptera acutorostrata), and Baird’s beaked whale (Berardius bairdii) caught in the Pacific Ocean. Identification was based on comparison of the relative retention times of the compound on two gas chromatographic columns of different polarities to those of an authentic standard. Furthermore, this identification was also supported by comparison of the full scan mass spectrometric data collected employing electron ionization (EI), positive ion chemical ionization (PICI), and electron capture negative ionization (ECNI). The concentrations of 2,2′diMeO-BB80 in the samples ranged from 12 to 800 ng/g lipid, making this consistently one of the most abundant compounds among those analyzed, including polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), and methoxylated PBDEs. The known occurrence of 3,3′,5,5′-tetrabromo-2,2′-biphenyldiol (2,2′-diOH-BB80) in the marine environment as a natural product suggests that its methylated derivative, 2,2′-diMeO-BB80, is also of natural origin. To obtain the necessary authentic standards, synthesis was performed of 2,2′-diMeO-BB80 and the known natural product 2′,6-dimethoxy-2,3′,4,5′-tetrabromodiphenyl ether (2′,6-diMeO-BDE68).
Introduction Persistent anthropogenic chlorinated organic compounds such as polychlorinated biphenyls (PCBs) and pesticides (e.g., * Corresponding author phone: + 34-93-400-6100; fax: + 3493-204-5904; e-mail:
[email protected]. † Stockholm University. ‡ Current address: Department of Environmental Chemistry, IIQAB, CSIC Jordi Girona, 10-18, 08034 Barcelona, Spain. § Health Sciences University of Hokkaido. | Daiichi College of Pharmaceutical Sciences. 8684
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ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 39, NO. 22, 2005
DDT, hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), chlordane, and dieldrin) are known to bioaccumulate in marine wildlife (1-5). Certain brominated organic compounds used as flame retardants (i.e., polybrominated biphenyls (PBBs) (6, 7), polybrominated diphenyl ethers (PBDEs) (2, 6-8), and isomers of 1,2,5,6,9,10-hexabromocyclododecane (HBCDD) (9)) have also been detected in marine mammals. During recent years, screening for such pollutants in the marine environment has resulted in the identification of organohalogen compounds that have proven to be or are most likely to be natural products (10-18). Such compounds include several hydroxylated (10) and methoxylated (10, 11) polybrominated diphenyl ethers (OH-PBDEs and MeOPBDEs), including monochlorinated OH- and MeO-PBDEs (10); a dimethoxylated polybrominated diphenyl ether (i.e., 2′,6-dimethoxy-2,3′,4,5′-tetrabromodiphenyl ether (2′,6diMeO-BDE68) (12)); four halogenated dimethylated bipyrroles (HDBPs) containing a 2,2′-bipyrrole backbone (1316); a heptachlorinated 1,2′-bipyrrole (i.e., heptachloro-1′methyl-1,2′-bipyrrole (Q1) (17)); and a halogenated monoterpene containing two bromine and three chlorine atoms (18). The goal of the present investigation was to determine the structure of a polybrominated compound detected in samples from marine mammals, gathered primarily in the coastal waters off Japan. Mass spectrometric analysis revealed a molecule ion of m/z ) 526 and an isotope pattern corresponding to substitution with four bromine atoms, and the molecule could be identified as 2,2′-dimethoxy-3,3′,5,5′tetrabromobiphenyl (2,2′-diMeO-BB80). The concentrations of this novel tetrabrominated compound in samples from marine mammals are reported, and its possible origin is discussed. For purposes of comparison, the concentrations of both a number of anthropogenic polybrominated flame retardants (BFRs) (i.e., common tetra- to heptaBDEs (BDE47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183) and HBCDD) and of other natural products (i.e., 6-methoxy2,2′,4,4′-tetrabromodiphenyl ether (6-MeO-BDE47), 2′-methoxy-2,3′,4,5′-tetrabromodiphenyl ether (2′-MeO-BDE68), and 2′,6-diMeO-BDE-68) were also determined. In addition, procedures for the synthesis of 2,2′-diMeO-BB80 and 2′,6diMeO-BDE68 were developed.
Experimental Procedures Chemicals. The polybrominated diphenyl ethers BDE-47, BDE-99, BDE-100, BDE-138, BDE-153, and BDE-154 (19, 20) and the methoxylated polybrominated diphenyl ethers 6-methoxy-2,2′,4,4′-tetrabromodiphenyl ether (6-MeO-BDE47) and 2′-methoxy-2,3′,4,5′-tetrabromodiphenyl ether (2′-MeOBDE68) (21) were all prepared as described previously. The syntheses of 2,2′-dimethoxy-3,3′,5,5′-tetrabromobiphenyl (2,2′-diMeO-BB80) and 2′,6-dimethoxy-2,3′,4,5′-tetrabromodiphenyl ether (2′,6-diMeO-BDE68) are described below. All solvents employed were of pesticide grade, and acids and other chemicals were of a pro analysis quality. Silica gel (99.995% purity and containing
