COMPARISON OF PCB QUANTITATION METHODS - REANALYSIS OF ARCHIVED SPECIMENS OF HERRING GULL EGGS FROM THE GREAT-LAKES

Eggs have been collected from colonies of Herring Gulls (Larus aegentatus) throughout the Great Lakes since 1970, and analyzed as a means of assessing trends in levels of organochlorine contaminants. PCBs were originally determined by packed-column GC-ECD as Aroclor 1254/1260 1:1 equivalents. Since 1986, forty-one individual congeners have been determined and summed to obtain SIGMA-PCB. In order to relate the new and old data and remove discontinuities due to method improvements, representative samples of a pooled gulls eggs from the 1970s and 1980s were retrieved from a specimen bank and reanalysed for individual PCB congeners. Conversion factors from Aroclor 1254/1260 1:1 to SIGMA-PCB were 0.450 for Lake Superior, 0.484 for Lake Huron, 0.444 for Lake Erie and 0.461 for Lake Ontario.