Identification of Unknown Brominated Bisphenol S Congeners in Contaminated Soils as the Transformation Products of Tetrabromobisphenol S Derivatives

Compared with tetrabromobisphenol A (TBBPA) and its derivatives, the skeletally similar chemicals tetrabromobisphenol S (TBBPS) and its derivatives have been rarely studied, and very little is known about their structures, environmental occurrence, and behaviors. In this study, a total of 84 soil samples from a chemical industrial park have been collected and analyzed to investigate the occurrence of TBBPS and its derivatives and to identify novel TBBPS analogs. TBBPS, TBBPS bis(2,3-dibromopropyl ether) (TBBPS-BDBPE), and three byproducts, TBBPS mono(allyl ether) (TBBPS-MAE), TBBPS mono(2-bromoallyl ether) (TBBPS-MBAE), and TBBPS mono(2,3-dibromopropyl ether) (TBBPS-MDBPE), have been detected with contents ranging from below detection limits to 1934.6 ng/g dw and with detection frequencies of 21.4-97.6%. In addition, another 5 unknown TBBPS analogs, tribromobisphenol S (TriBBPS), 2,2',6'-TriBBPS-MAE (TriBBPS-MAE(3.2)), 2,6,2'-TriBBPS-MAE (TriBBPS-MAE(3.4)), 2',6'-DBBPS-MAE (DBBPS-MAE(2.0)), and 2,6-DBBPS-MAE (DBBPS-MAE(2.6)), have been identified in these soil samples by untargeted mass spectrometry screening. These unknown analogs have also been observed in laboratory transformation experiments of TBBPS-MDBPE conducted under reducing conditions. TriBBPS-MAE(3.4) and DBBPS-MAE(2.6) were more likely to be produced than TriBBPS-MAE(3.2) and DBBPS-MAE(2.0) due to the stereoselectivity of the transformation. TriBBPS-MAE(3.4) and DBBPS-MAE(2.0) were more stable, resulting in higher detection frequencies of these compounds in soil samples. Ether bond breakage and debromination contributed to the generation of these novel products. The results provide new information on the behaviors of TBBPS and its derivatives in the environment.