TY - CONF A1 - Esslinger, Susanne A1 - Becker, Roland A1 - Müller-Belecke, A. A1 - Jung, Christian A1 - Nehls, Irene T1 - Bioisomerization of HBCD: Results of feeding experiments with pure Gamma-HBCD enantiomers N2 - 1,2,5,6,9,10-hexabromocyclododecane (HBCD), a widely used flame retardant, is an ubiquitous contaminant in the environment. Still, only little is known about the distribution and behavior in the environment such as bioaccumulation or biotransformation of HBCD stereoisomers. In order to investigate enrichment and possible bioisomerization of HBCD stereoisomers, Mirror Carps were exposed to pure (+)- and (-)-γ-HBCD, randomly sampled after a predefined specific period and subjected to enantiomer-specific determination of α-, β-, and γ- HBCD. No evidence for the isomerization of HBCD stereoisomers was observed in Mirror Carp fillets. T2 - Dioxin 2009 - 29th International symposium on halogenated persistent organic pollutants / Organohalogen compounds CY - Beijing, China DA - 2009-08-23 PY - 2009 UR - http://www.dioxin20xx.org/pdfs/2009/09-103.pdf VL - 71 SP - 000487 EP - 000492 CY - Beijing, China AN - OPUS4-21187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Köppen, Robert A1 - Becker, Roland A1 - Jung, Christian A1 - Nehls, Irene T1 - On the thermally induced isomerisation of hexabromocyclododecane stereoisomers N2 - The interconversion of the stereoisomers contained in technical 1,2,5,6,9,10-hexabromocyclododecane, a major brominated flame retardant increasingly found in the environment and in biota, was investigated at elevated temperatures. The application of pure enantiomers of the three constituents α-, β-, and γ-HBCD enabled the unambiguous elucidation of the individual isomerisation reactions as well as the quantification of all respective rate constants. At 160 °C the rate constants range over two orders of magnitude from 1.50 × 10-3 to 1.88 × 10-5 mol(%) s-1. A preliminary mechanistic explanation for the differences of the rate constants which govern the composition of HBCD diastereomers at equilibrium is given. KW - Flame retardant KW - Diastereomers KW - Enantiomers KW - Rearrangement KW - Kinetics KW - HBCD PY - 2008 DO - https://doi.org/10.1016/j.chemosphere.2007.11.009 SN - 0045-6535 SN - 0366-7111 VL - 71 IS - 4 SP - 656 EP - 662 PB - Elsevier Science CY - Kidlington, Oxford AN - OPUS4-17753 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Köppen, Robert A1 - Becker, Roland A1 - Emmerling, Franziska A1 - Jung, Christian A1 - Nehls, Irene T1 - Enantioselective Preparative HPLC Separation of the HBCD-Stereoisomers from the Technical Product and Their Absolute Structure Elucidation Using X-Ray Crystallography N2 - 1,2,5,6,9,10-Hexabromocyclododecane (HBCD) is a widely used flame retardant, which tends to persist in the environment and accumulates in biota. The six stereoisomers (three racemates named α-, β-, and γ-HBCD) of the technical mixture were isolated with high-performance liquid chromatography (HPLC). Direct separations were performed on a chiral stationary phase containing permethylated -cyclodextrin (NUCLEODEX -PM column) and the pure enantiomers of α-, β-, and γ-HBCD were physically characterized for the first time. The absolute configurations of all six isomers were determined by anomalous dispersion using single crystal X-ray crystallography. Optical rotations αD in tetrahydrofuran were +4.2/-4.0 (α-HBCD), +26.1/-27.5 (β-HBCD), and +68.0/-66.3 (γ-HBCD). The sense of rotation could be correlated with the absolute configurations of α-, β-, and γ-HBCD enantiomers and their order of elution on a chiral permethylated β-cyclodextrin-bonded stationary phase. The diastereomers α-, β-, and γ-HBCD displayed distinctly different melting points as well as 1H-, 13C NMR, and IR spectra. KW - Brominated flame retardant KW - Chiral separation KW - Anomalous dispersion KW - Crystal structures KW - Optical rotation KW - Absolute configuration PY - 2007 DO - https://doi.org/10.1002/chir.20366 SN - 0899-0042 SN - 1520-636X VL - 19 IS - 3 SP - 214 EP - 222 PB - Wiley-Liss CY - New York, NY AN - OPUS4-14718 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Köppen, Robert A1 - Becker, Roland A1 - Jung, Christian A1 - Piechotta, Christian A1 - Nehls, Irene T1 - Investigation of extraction procedures and HPLC-DAD/MS for the determination of the brominated flame retardant tetrabromobisphenol A bis(2,3-dibromopropylether) in environmental samples N2 - A method for the determination of the novel brominated flame retardant tetrabromobisphenol A bis(2,3-dibromopropylether), 1,1'-(isopropylidene)bis[3,5-dibromo-4-(2,3-dibromo-propoxy)-benzene] (TBBPA-dbpe), was developed. Technical TBBPA-dbpe was purified and the results of a thorough physical characterisation are reported. The application of APCI-MS is discussed and the fragmentation patterns are described. Quantification of TBBPA-dbpe was done by HPLC-DAD using external calibration. The validation of the method was accomplished using sediment and sewage sludge samples spiked with defined amounts of authentic TBBPA-dbpe. The average recovery rates of TBBPA-dbpe from spiked samples ranged from 35 to 91% (sediment) and from 57 to 98% (sewage sludge) depending on the respective extraction method. Pressurised fluid extraction (PFE) and fluidised bed extraction were superior to classical Soxhlet and sonication procedures and yielded recovery rates between 90 and 98% with relative standard deviations of 2%. The limits of detection (DTC), identification (ID) and determination (DTM) using HPLC-DAD were 10, 21 and 30 ng g-1 in sediment and 22, 44 and 72 ng g-1 in sewage sludge, respectively. KW - Extraction KW - TBBPA-dbpe KW - Sewage sludge KW - Sediment KW - LC-MS KW - Mass spectrometry KW - APCI KW - HPLC-DAD PY - 2006 DO - https://doi.org/10.1007/s00216-006-0339-z SN - 1618-2642 SN - 1618-2650 VL - 384 IS - 7-8 SP - 1485 EP - 1492 PB - Springer CY - Berlin AN - OPUS4-12255 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppen, Robert A1 - Becker, Roland A1 - Emmerling, Franziska A1 - Jung, Christian A1 - Nehls, Irene T1 - HBCD enantiomers: absolute configurations and thermal rearrangement T2 - Organohalogen Compounds PY - 2006 UR - http://www.dioxin20xx.org/pdfs/2006/06-466.pdf VL - 68 SP - 1991 EP - 1994 PB - Norwegian Institute of Public Health AN - OPUS4-14540 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -