高比科技 侯先生 13691497252 Weathering of Aroclor mixes that have been in the environment for more than 30 years and changes in Aroclor patterns in tissue samples, due to bioaccumulation have made identification and quantification of Aroclor mixes difficult. Consequently, many laboratories are analyzing long lists of PCB congeners, using the data to determine specific congener patterns, and compi領(lǐng) congener results to obtain an accurate total PCB concentration. Identification and quantification of PCB congeners is chromatographically challenging because there are 209 possible combinations in which chlorine atoms can be added to the biphenyl structure, ranging from addition of single chlorine (monochlorobiphenyls) to addition at every available carbon atom (decachlorobiphenyl). In 1996, George Frame published work he performed in order to determine which PCB congeners are present in Aroclor mixes. Using this work as a guide, the list of 209 possible PCB congeners can be reduced to a target list of 158 congeners. Several congeners not found in Aroclors but found in animal tissues, such as PCB#169, have been added. The list encompasses the seven European indicator compounds and the 12 most toxic congeners listed by the World Health Organization (WHO) list.