Chromatographic enrichment and enantiomer separation of axially chiral polybrominated biphenyls in a technical mixture

• Published in: Journal of Chromatography A Vol. 973; no. 1; pp. 123 - 133
• Main Authors: Berger, Urs, Vetter, Walter, Götsch, Arntraut, Kallenborn, Roland
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 11.10.2002; Elsevier
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography, Gas; Chromatography, High Pressure Liquid - methods; Cyclodextrins; Exact sciences and technology; Polybrominated biphenyls; Polybrominated Biphenyls - chemistry; Polybrominated Biphenyls - isolation & purification; Stereoisomerism; Atropisomerism; Cyclodextrins; Enantiomer separation; Polybrominated biphenyls; Firemaster BP-6; Electron capture detector; Separation; Coupled method; Benzene derivatives; HPLC chromatography; Bromocarbon; Chiral stationary phase; Experimental study; Gas chromatography; Cyclodextrin; Atropoisomerism; Ultraviolet detector; Optical resolution; Enantiomer; Mass spectrometry
• ISSN: 0021-9673
• DOI: 10.1016/S0021-9673(02)01112-3

The separation properties of different chromatographic methods regarding the enantioselective separation of axially chiral (atropisomeric) polybrominated biphenyls (PBB) were studied. For this purpose, the technical hexabromobiphenyl product Firemaster BP-6 ® was characterised by gas-chromatography coupled to electron capture detection (GC/ECD) and electron-capture negative ion mass spectrometry (GC/ECNI-MS) as well as by liquid chromatographic fractionating on active carbon and celite. Twelve individual PBBs including potential atropisomeric PBBs were isolated from Firemaster BP-6 by reversed-phase high-performance liquid chromatography (HPLC) on three serially coupled octadecylsilane columns. Six of the 12 isolated PBBs (three tri- ortho and di- ortho substituted PBBs, respectively) were separated into atropisomers on a HPLC column containing permethylated β-cyclodextrin on silica. Moreover, the temperature dependency of the enantiomer separations is discussed. Gas chromatographic enantiomer separation of PBBs is a very demanding task due to high elution temperatures. However, the atropisomers of one tri- ortho substituted PBB congener (PBB 149) could be resolved on a column coated with randomly modified heptakis(6- O- tert.-butyldimethylsilyl-2,3-di- O-methyl)-β-cyclodextrin in OV 1701.