title: Enantioselective semipreparative HPLC separation of PCB metabolites and their absolute structure elucidation using electronic and vibrational circular dichroism.
abstract: Polychlorinated biphenyls (PCBs) remain one of the most important groups of environmental contaminants. The fate (transformation) as well as the toxicological implications of the different metabolism steps are subject to considerable debate. The aim of this study is to start a comprehensive investigation of atropisomeric PCB metabolites, i.e., hydroxy, methoxy, methylthionyl, and methylsulfonyl PCBs in different biota. For this purpose, enantioselective semipreparative liquid chromatography is used to obtain pure enantiomers of PCB metabolites. Electronic circular dichroism (UV-CD) and vibrational circular dichroism (VCD) in combination with computational techniques were applied to determine their absolute structures. Approximately 18-25 mg of each enantiomer of the following metabolites were obtained using semipreparative HPLC on beta-cyclodextrin-based columns: 4-MeO-CB149, 4-MeS-CB149, 4-MeSO2-CB149, 3-MeS-CB149, and 3-MeSO2-CB149. The enantiomeric purity of the separated enantiomers was in the range of 95.0-99.9%. Rotational angles and absolute configurations were also determined. This study establishes a sound method for future preparation and absolute structure determination of compounds belonging to the same class.
authors.affiliation: University of Hamburg, Institute of Organic Chemistry, Hamburg, Germany. Hai.Pham-Tuan@chemie.uni-hamburg.de
authors.forename: Hai
authors.initials: H
authors.lastname: Pham-Tuan
authors.forename: Christina
authors.initials: C
authors.lastname: Larsson
authors.forename: Frank
authors.initials: F
authors.lastname: Hoffmann
authors.forename: Ake
authors.initials: A
authors.lastname: Bergman
authors.forename: Michael
authors.initials: M
authors.lastname: Fröba
authors.forename: Heinrich
authors.initials: H
authors.lastname: Hühnerfuss
mesh_terms: D002845:Chromatography; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002853:Chromatography, Liquid; D002942:Circular Dichroism / Q000379:methods*; D004785:Environmental Pollutants; D008968:Molecular Conformation; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D012984:Software; D013237:Stereoisomerism; D014466:Ultraviolet Rays; D047392:beta-Cyclodextrins / Q000737:chemistry
chemical_list: D004785:Environmental Pollutants; D047392:beta-Cyclodextrins; D011078:Polychlorinated Biphenyls; C031215:betadex