title: Determination of ten hexabromocyclododecane diastereoisomers using two coupled reversed-phase columns and liquid chromatography/tandem mass spectrometry.
abstract: BACKGROUND
  Hexabromocyclododecanes (HBCDs) are raising concern due to their potential persistence, bioaccumulation and toxicity. Apart from the widely reported isomers α-, β-, γ-HBCD, other HBCD diastereoisomers such as δ-HBCD have been also recently found in environmental media and biota. These newly reported diastereoisomers might give more insight into the degradation and biotransformation of HBCDs.
  
  
  METHODS
  A reversed-phase C18 column coupled to a C8 column was used to improve the chromatographic resolution. A gradient mobile phase consisting of methanol, acetonitrile, and water, as well as tandem mass spectrometry parameters, were optimized. Ten HBCD diastereoisomers were finally determined by liquid chromatography/tandem mass spectrometry in multiple reaction monitoring mode with negative electrospray ionization.
  
  
  RESULTS
  Eight of the ten HBCDs could be chromatographically separated by using the coupled reversed-phase columns. Results of the method validation indicate high reproducibility and good sensitivity. The limit of detection ranged from 0.4 to 0.8 pg, and the relative standard deviations of intra- and inter-day injections ranged from 1.8 to 5.1% and from 2.7 to 9.5%, respectively. The developed method was further applied to the analysis of HBCDs in HBCD commercial products and soil samples. δ-, η-, θ-, and ε-HBCD were detected in commercial products and soil samples.
  
  
  CONCLUSIONS
  The present study revealed that δ-, η-, θ-, and ε-HBCD might occur ubiquitously in environmental media and biota. These newly reported diastereoisomers may help us to better understand the fate and transformation of HBCDs in the environment.
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangdong Key Laboratory of Environment Protection and Resource Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China; University of the Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Han
authors.forename: Han
authors.initials: H
authors.lastname: Song
authors.forename: Shutao
authors.initials: S
authors.lastname: Gao
authors.forename: Xiangying
authors.initials: X
authors.lastname: Zeng
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Yu
authors.forename: Yunjiang
authors.initials: Y
authors.lastname: Yu
authors.forename: Guoying
authors.initials: G
authors.lastname: Sheng
authors.forename: Jiamo
authors.initials: J
authors.lastname: Fu
mesh_terms: D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase / Q000379:methods*; D006842:Hydrocarbons, Brominated / Q000032:analysis* / Q000737:chemistry*; D057230:Limit of Detection; D015203:Reproducibility of Results; D012987:Soil / Q000737:chemistry; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D006842:Hydrocarbons, Brominated; D012987:Soil; C089796:hexabromocyclododecane