The extract were analyzed for phthalate ester using the 
selected ion monitoring mode. Chromatograms of the spiked and 
unspiked oysters are shown in Figures l 4 and 15. Even though 
percent abundance of m/e 149 is linolenic acid is 3 percent, its 
high concentration in the injected extract makes it clearly 
evident in the m/e 149 selected ion monitoring team. Indeed, 
all four sets of peaks similarly appear in the m/e 149 mass 
chromatogram. While the DEP and DBP are resolved from inter¬ 
fering peaks, DEHP co-elutes with the linolenic acid group. 
The DEHP concentration must be greater than 2 ppm in order to 
make the interfering background insignificant and obtain mean¬ 
ingful quantitative results. 
The recoveries of DEP, DBP and DEHP from spiked (20 ppm) 
oyster tissue takers through the entire drying and extraction 
procedure were 60+6, 96+5, and 100 + 15 percent, respective¬ 
ly. The smaller recovery for DEP is assumed to be due to voli- 
tization during the freeze drying process. 
The measured levels of alkyl phthalates in oyster tissue are 
reported in Table 11 along with values for sediment samples 
taken from the same zone. 
As discussed earlier, the octanol-water partitioning model 
predicts that the hydrophobic phthalates will be concentrated 
in the total lipid portions of the oysters relative to the sur¬ 
rounding water. We did not measure lipid content per se , but 
the oyster and sediment values were compared on the basis of 
the measured total organic carbon content which was measured. 
The oyster contained a 16-fold higher concentration of organic 
carbon than the sediment. Accordingly, the alkyl phthalate 
concentration is predicted by the partition model to be approx¬ 
imately 16-fold higher than that in the sediment. This pre¬ 
diction does not consider any mechanism other than simple 
partitioning. Table 17 shows that the oyster-to-sediment ratio 
of total phthalate ester residue is consistent with this model. 
At the two sites where contiguous oyster and sediment samples 
were obtained, the ratio is 16:1 (Buoy Rock) and 23:1 (Spaniard 
Point). This suggests that the surficial analysis of stratified 
(anoxic, nonbioturbated) taken nearby oyster beds may provide a 
basis for predicting the concentration of phthalates in the 
nearby oysters. It is also apparent that the level of phtha¬ 
lates in the oysters from the Chester River do not signifi¬ 
cantly differ from the reference sample of commercial oysters, 
also taken from the northern Chesapeake Bay. 
Table 18 shows that the measured levels of alkyl phthalates 
in oysters range from 0.45 to 1.5 ppm (wet basis). The U.S. 
Bureau of Sport Fisheries and Wildlife reported recently (Mayer 
et al. 1972) a range of 0.2 to 3.2 ppm of alkyl phthalates in 
channel catfish and walleyes from various parts of North 
America. Also, a survey of 145 catfish farms (Haudet 1970) 
77 
