Levels, isomer profiles and chiral signatures of particle-bound hexabromocyclododecanes in ambient air around Shanghai, China.

Hexabromocyclododecanes (HBCDs) have been considered candidate persistent organic pollutants, however, environmental data on their presence in China, a major world market, are limited. In this study, airborne particle-bound HBCDs in Shanghai, China were quantified with liquid chromatography-tandem mass spectrometry, and their total concentrations varied from 3.21 to 123 pg/m(3). The industrial area showed about three times higher HBCD levels than the urban areas. Gamma-HBCD dominated in particle-associated HBCDs in the industrial area, while α-HBCD was the major diastereomer of the urban areas, which is quite different from the pattern of technical products. Besides α-, β- and γ-HBCDs, δ-HBCD was also detected in all samples (0.09-6.31 pg/m(3)), while no ɛ-HBCD was found. Airborne β- and γ-HBCDs were racemic in most studied areas due to their chiral signatures showing no significant difference from commercial mixture. Fractions of (+)-α-HBCD (0.417-0.467), however, suggested the enrichment of (-)-α-HBCD and the involvement of enantioselective bioprocesses.