Legacy PBDEs and NBFRs in sediments of the tidal River Thames using liquid chromatography coupled to a high resolution accurate mass Orbitrap mass spectrometer

Surface sediment samples (n = 45) were collected along a 110 km transect of the river Thames in October 2011, starting from Teddington Lock out through the industrial area of London to the southern North Sea. Several legacy and novel brominated flame retardants (NBFRs) were analysed, including 13 polybrominated diphenyl ethers (PBDEs) (congeners 17, 28, 47, 99, 100, 153, 154, 183, 196, 197, 206, 207 and 209), hexabromocyclododecane (HBCDDs), tetrabromobisphenol A (TBBPA), hexabromobenzene (HBB), 2,4,6-tribromophenol (TBP), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (EH-TBB or TBB), bis(2-ethylhexyl) tetrabromophthalate (BEH-TEBP or TBPH), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), pentabromoethylbenzene (PBEB), anti/syn-dechlorane plus (a/s-DP), 2,2',4,4',5,5'-hexabromobiphenyl (BB153) and α-,β-1,2-dibromo-4-(1,2-dibromoethyl) cyclohexane (α-,β-DBE-DBCH or TBECH). A novel analysis method based on liquid chromatographic separation, followed by high resolution accurate mass detection using the Orbitrap platform was used for quantification. Results revealed that BDE-209 had the highest concentrations (<0.1 to 540 μg kg-1 dw) and detection frequency, accounting for 95% of all PBDE congeners measured. Indicative evidence of debromination of the PentaBDE technical mixture was observed through elevated relative abundance of BDE-28 in sediment compared to the Penta-BDE formulation. NBFRs were detected at comparable levels to PBDEs (excluding BDE-209), which indicates increasing use of the former. Spatial trend analysis showed that samples from industrial areas had significantly higher concentrations of Σ12PBDEs, ΣHBCDDs, TBBPA, BEH-TEBP, BTBPE and TBP. Three locations showed high concentrations of HBCDDs with diastereomer patterns comparable to the technical mixture, which indicate recent input sources to the sediment.