No abstract

Halogenated natural products (HNPs) have been increasingly reported to occur in marine wild life from all oceans. Several HNPs, such as 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1,2'-bipyrrole (1) and 4,6-dibromo-2-(2',4'-dibromo)phenoxyanisole (2'-MeO-BDE 68 or BC-2), were detected at particularly high concentrations in dolphins from Queensland/Australia. About half of the coastline of Queensland (approximately 2500 km) is covered by the Great Barrier Reef, a rich ecosystem hosting a huge variety of species, many of which are known to produce natural compounds. In this study, semipermeable membrane devices (SPMDs) were deployed as passive samplers for about 30 days at 12 marine and 2 nonmarine sites (i.e., rivers) along the Great Barrier Reef as part of a routine monitoring program during November 2007 and May 2008. Q1 and 2'-MeO-BDE 68 were detected at the marine sites with frequencies of about 65% but not in any sample from the two rivers. Further HNPs (2,4,6-tribromophenol, TBP; 2,4,6-tribromoanisole, TBA; 2,2'-dimethoxy-3,3'5,5'-tetrabromobiphenyl, 2,2'-diMeO-BB 80 or BC-1; 3,5-dibromo-2-(2',4'-dibromo)phenoxyanisole, 6-MeO-BDE 47 or BC-3; and 3,5-dibromo-2-(3',5'-dibromo,2'-methoxy)phenoxyanisole, 2',6-diMeO-BDE 68 or BC-11) were detected as well with frequencies of 18-97% in the marine samples, but no polybrominated flame retardants were detected. The highest amount of a single HNP, 2.3 microg/SPMD, was determined for TBP, which had a frequency of detection of only 46%. The maximum (average) amount in the SPMDs from marine sites was 44 ng (12 ng) for (1 and 115 ng (20 ng) for 2'-MeO-BDE 68. A first order kinetic model was used to estimate concentrations of the HNPs in the water phase. Based on the depuration of performance reference compounds obtained at one of the sites, we assumed a sampling rate of 16 L/day. We used this sampling rate to estimate that the highest and average available concentrations of Q1 in the water during the deployment of the SPMD were 97 and 25 pg/L, respectively. The estimated maximum water concentrations of 2'-MeO-BDE 68, 2,2'-diMeO-BB 80, 6-MeO-BDE 47, and 2',6-diMeO-BDE 68 were on average 2-5.5 fold higher than that of Q1. The results confirm that the HNPs are produced throughout the Great Barrier Reef, which appears to be a significant source of these compounds.

Gas chromatography in combination with electron capture negative ion mass spectrometry (GC/ ECNI-MS) is a sensitive method for the determination of polybrominated compounds in environmental and food samples via detection of the bromide ion isotopes m/z 79 and 81. The standard reagent gas for inducing chemical ionization in GC/ECNI-MS is methane. However, the use of methane has some drawbacks as it promotes carbonization of the filament and ion source. In this study, we explored the suitability of nitrogen as reagent gas for the determination of brominated flame retardants (polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), allyl-2,4,6-tribromophenyl ether (ATE) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE)) and halogenated natural products (for instance, methoxylated tetrabrominated diphenylethers and polybrominated hexahydroxanthene derivatives). An ion source temperature of 250-C and a nitrogen pressure of 7 Torr in the ion source gave the highest response for m/z 79 and 81 of virtually all investigated polybrominated compounds. Using these conditions, nitrogen-mediated GC/ECNI-MS usually gave higher sensitivity than the method with methane previously used in our lab. In addition, the ion source was not contaminated to the same degree and the lifetime of the filament was significantly increased. Moreover, the response factors of the different polybrominated compounds with the exception of 2,4,6-tribromophenol were more uniform than with methane. Nitrogen is available at very high purity at relatively low price.

Polybrominated organic compounds are ubiquitous throughout the environment. This generic term comprises several classes of brominated flame retardants (e.g., polybrominated diphenyl ethers, polybrominated biphenyls, hexabromocyclododecane, dibromopropyltribromophenyl ether, 1,2-bis(2,4,6-tribromophenoxy)ethane) as well as a range of marine halogenated natural products (HNPs). Here we present gas chromatography retention times and elution orders (on DB-5) of 122 polybrominated compounds that may be found in food and environmental samples. Organobromine compounds in fish samples determined with gas chromatography interfaced to electron-capture negative ion mass spectrometry (GC/ECNI-MS) are discussed. The environmental relevance and important mass spectrometric features of the compounds are described as well. Our database aims to support the closer inspection and identification of peaks in gas chromatograms and to initiate dedicated screening for less frequently studied organobromines in samples.