Abstract
Two gas chromatography/mass spectrometry (GC/MS) methods for the determination of polybrominated biphenyls (PBBs) by isotope dilution analysis (IDA) using (13)C(12)-PBB 153 in the presence of polybrominated diphenyl ethers (PBDEs) were compared. Recovery of (13)C(12)-PBB 153 which was added to the extracted lipids before sample purification was commenced ranged from 88-117% (mean value 98.2 +/- 8.9%). Nevertheless, IDA analysis of PBBs using (13)C(12)-labelled congeners is limited by the potential co-elution of PBBs with polybrominated diphenyl ethers (PBDEs). The pair PBB 153 and BDE 154 was inspected since M(+) and [M-2Br](+) ions of (13)C(12)-PBB 153 and BDE 154 were only separated by 4 u. Gas chromatography/electron ionization high-resolution mass spectrometry with selected ion monitoring (GC/EI-HRMS-SIM) was suitable when m/z 475.7449 and m/z 477.7429 were used for (13)C(12)-PBB 153 because they are below the monoisotopic peak of the [M-2Br](+) fragment ion of hexaBDEs at m/z 479.7. Gas chromatography/electron capture negative ion tandem mass spectrometry selected reaction monitoring (GC/ECNI-MS/MS-SRM) measurements could be applied because (13)C(12)-PBB 153 and BDE 154 were separated by GC on a 25-m Factor Four CP-Sil 8MS column.Comparative measurements with GC/EI-HRMS-SIM and GC/ECNI-MSMS-SRM were carried out with samples of Tasmanian devils from Tasmania (Australia), an endangered species due to a virus epidemy which has already proved fatal for half of the population. Both techniques verified concentrations of PBB 153 in the range 0.3-11 ng/g lipids with excellent agreement of the levels in all but two samples. The PBB residue pattern demonstrated that PBB pollution originated from the previous discharge with technical hexabromobiphenyl which is dominated by PBB 153. Other congeners such as PBB 132 and PBB 138 were detected in the Tasmanian devils but the proportions relative to PBB 153 were lower than in the technical product. Samples of healthy and affected Tasmanian devils showed no significant difference in the PBB pollution level. The PBB concentrations in the Tasmanian devils were significantly below those causing toxic effects. On the other hand, PBB concentrations were one level or even higher than PBDEs.
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