where : 



LOD = Single isomer limits of detection (ng/g) for a 

 congener class; 

 He = Height of congener class isomer; 

 Qis = Quantity of internal standard (ng) ; 

 His = Peak height of internal standard; 

 W = Sample weight (g) 

 Rf = Response factor; and 

 2.5 = Signal-to-noise ratio. 



RESULTS 



Isomers of PCDD/PCDF's were detected at all sample 

 locations, higher levels of PCDD/PCDF were found in the 

 composite, wetland and upland samples, compared with the 2 00 

 East (2E8510) and South Reference (RS8510) samples (Table 4) . 

 This table also includes information on the recovery of congeners 

 spiked into a sample and the method blank levels. The 

 procedural blank levels were either not detectable or 

 insignificant measurable levels of some PCDDs and PCDFs were 

 found in all of the samples analyzed (Table 4) and, therefore, 

 the sample results have not been corrected for laboratory or 

 field blank levels. They have been corrected, however, for 

 extraction efficiency and cleanup losses. A detection limit is 

 listed for samples in which a particular congener was not 

 detected. The concentration of the 2 , 3 , 7 , 8-substituted PCDD/PCDF 

 which coeluted with the internal standards are also given in 

 Table 4. In some cases, as indicated in Table 4, the peaks 

 quantified could include more than one compound. On the DB-5 

 capillary gas chromatographic column 2 , 3 , 7 , 8-tetra-CDF , 

 1,2,3 ,7,8-penta-CDF, 1, 2 , 3 , 6, 7 , 8-hexa-CDF, and 1, 2 , 3 , 4 , 7 , 8-hexa- 

 CDF are not easily resolved from certain other isomers in their 

 congener class, and thus, may contain contributions from other 

 isomers. For example, 2 , 3 , 7 , 8-tetra-CDF may coelute with 

 1, 2 , 4, 9-tetra-CDF, 2 , 3 , 4 , 7-tetra-CDF, 2 , 3 , 4 , 8-tetra-CDF, and 

 2,3,4, 6-tetra-CDF . 



The number of resolved peaks quantified as PCDD/PCDF in 

 each congener group are given in Table 5. Each resolved peak may 

 contain more than one CDD/CDF isomer. The octa- CDD/CDF, for 

 which there exists only one isomer of each class, are not listed 

 in Table 5. Several isomers were observed for most congener 

 classes. In general, hepta-and octa-CDD/CDF were the most 

 abundant congener classes in the sediment samples (Table 4) . 



The recovery of tetra- through octa- CDD/CDF averaged 

 61 percent (Table 6) , which is within the expected range of 

 recoveries for samples subjected to florisil chromatographic 

 cleanup. Chlorine isotope ratios for samples that contained 

 PCDD/PCDF isomers are summarized in Table 7, and all met 

 acceptance criteria. 



