Purification of polybrominated biphenyl congeners.

A commercial preparation of polybrominated biphenyls (Firemaster BP-6) was fractionated by preferential acetone solubilization and a number of PBB congeners were purified from the resulting fractions by repeated recrystallization, alumina adsorption column chromatography, and reversed-phase Lipidex-500 column chromatography. The applicability of reversed-phase Lipidex-5000 chromatography for the separation of highly structurally similar brominated biphenyl congeners that otherwise could not be separated by alumina chromatography or recrystallization was demonstrated. In total, seven congeners were purified, including one whose structure was assigned as 2,3,4,5,3',4'-hexabromobiphenyl.