The International Mussel Watch 



C S am = hsam x RF x (IS x l/RF is x l/h is ) x 1/M (ng g' 1 wet wt) 

 Under ideal conditions, XF = XFj s . 



The construction of an analysis data reporting format for PCB's is not without problems. 

 Background information for the selection of the reporting criteria used here is given below. 



The number of PCB congeners which can be analyzed accurately under present conditions 

 is restricted to those that are well separated from interfering compounds on the SE-54 column. In 

 addition, the list is limited to those congeners that are available as reference compounds in 

 sufficiently pure forms. The congeners that satisfy these requirements and that have been 

 identified in environmental samples and commercial mixtures and that are in available standards are 

 listed in Table D.4. 



These components should be identified and evaluated quantitatively. The concentrations of 

 these compounds in the sample matrix are calculated according to the formulae given in this 

 section. Although a list of concentrations of the major PCB congeners present in environmental 

 samples represents, both qualitatively and quantitatively, the most detailed and accurate information 

 on PCB's in the particular sample, this does not result in the most convenient form for comparison 

 purposes. For qualitative purposes, e. g., when comparing the composition of PCB mixtures 

 from different samples, it would be more convenient to have data on the relative contribution of 

 each PCB congener in the mixture. This information can be readily obtained by summing the 

 concentrations of the individual congeners (PCB sum ) and calculating the percentage of each 



component in the mixture. The percentage contributions, are not dependent on the way the 

 absolute concentration (e.g., in \±g g~l) have been expressed nor whether on a wet, dry or lipid 

 weight basis. Though the absolute concentration may differ widely, qualitative comparisons 

 between PCB mixtures in different samples is facilitated. For example, when evaluating the 

 differences in composition of PCB's in organisms, the dependence on age, sex, season, etc. may 

 play an important role in the distribution of individual congeners. Thus, in addition to the total 

 PCB concentration, the relative contribution of each individual congener to PCB sum will provide 



important information on the behavior of the individual congeners in the sample matrix. 



104 



