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PCB Groupings and FormulationsToxicity and AbundancePCB Congeners can be grouped according to their presence in thetechnical mixtures (i.e. Aroclors) and according to their toxicity, generallyfalling into the following pattern:Congeners that contain fewer chlorine substitutions in the ortho positionsare more toxic than those having more chlorines in those positions. Themost toxic are the tetra, penta and hexachlorobiphenyl congeners that areunsubstituted in the ortho position (which makes them dioxin-like).Analytical ConvenienceTo obtain meaningful analytical data, the congeners need to beformulated into groupings of solutions that are all resolved on a gaschromatographic column. The “holy grail” of columns, the single columnby which all 209 congeners are separated has, to this date, eluded all GCcolumn manufacturers.There are 2 columns that are closest to achieving the “holy grail” statusof separating all the PCB congeners. They are Agilent DB-XLB & SGE'sHT 8 which resolve all but 4 pairs of significant congeners and 5 pairs ofminor congeners.George Frame and his co-workers at General Electric Company havecoordinated a seminal study of specially formulated PCB groups - fiveof which are composed of the congeners contained in Aroclors, theremaining four mixtures contain those congeners generally absent inAroclors. AccuStandard prepared and supplied the nine mixtures used inDr. Frame's study from its inventory of the 209 pure congeners.The above nine mixtures were then tested on 17 different columns byindependent laboratories and column manufacturers. The resultingchromatographic retention time and response data was compiled andpublished. This information has proven invaluable for identification andquantification of the different Aroclors as well as for congener specificanalysis.PCBsPhysical, Spectral, andChromatographic Properties ofall 209 Individual PCB CongenersAccuStandard's FT/IR, Mass Spectral data, melting point andchromatographic information along with chromatographic datafrom George Frame's study is available in the book.PCB-BOOK-002 $ 25Tel. 800-442-5290 / 203-786-5290 • Fax 203-786-5287 • AccuStandard.com17