Identification of hydroxylated metabolites in 2,2′,4,4′-tetrabromodiphenyl ether exposed rats

Faeces from day 1–5 of orally administered 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) in rat have been analysed for hydroxylated metabolites. Six hydroxylated tetrabrominated diphenyl ethers, as well as three hydroxylated tribrominated diphenyl ethers found, were structurally identified. They were 2′-hydroxy-2,4,4′-tribromodiphenyl ether, 3′-hydroxy-2,4,4′-tribromodiphenyl ether, 4′-hydroxy-2,2′,4-tribromodiphenyl ether, 6-hydroxy-2,2′,4,4′-tetrabromodiphenyl ether, 2′-hydroxy-2,3′,4,4′-tetrabromodiphenyl ether, 3-hydroxy-2,2′,4,4′-tetrabromodiphenyl ether, 5-hydroxy-2,2′,4,4′-tetrabromodiphenyl ether, 4′-hydroxy-2,2′,4,5′-tetrabromodiphenyl ether and 4-hydroxy-2,2′,3,4′-tetrabromodiphenyl ether. The analysis was performed using gas chromatography–mass spectrometry (GC–MS). The identification of the hydroxylated polybrominated diphenyl ether (OH-PBDE) metabolites in the rat faeces was supported by similar relative retention times (RRTs) versus 2,2′,3,4,4′,5-hexabromodiphenyl ether (BDE-138) on two columns of different polarities compared to the authentic references. The identification of the OH-PBDE metabolites was also supported by full scan electron ionisation mass spectra. Two of the identified OH-PBDE metabolites have identical structures as natural products, which previously have been isolated from marine sponges and an ascidian.