Treated flake food was extracted with methylene chloride to confirm the nominal concentrations of BaP. Approximately 10 mg of flakes were extracted right before day 0 and on days 7 and14 with 2–3 mL of methylene chloride. A known concentrationof a surrogate standard, benzo[a]pyrene-d12, was added to eachsample to yield a final concentration of 0.2 g/mL. Samples werevortexed for 30 s and centrifuged for 7 min at 2000 rpm (668 × g).Samples were then blown to dryness with N2and brought backup with a known volume of hexane. A known concentration ofinternal standard, fluorene-d10, was added to each sample todetermine extraction efficiency. Samples were run on the GC/MSunder the selected ion mode to quantitate the concentration ofBaP in each sample. BaP was not identified in the acetone-treatedsamples. Actual BaP concentrations of the treated flakes were:10.44 ± 0.4, 113.6 ± 2.3, and 1012 ± 30.7 g BaP/g flake equiva-lent to 0.209 ± 0.008, 2.27 ± 0.046, and 20.25 ± 0.614 g BaP/g fish,respectively. Percent recoveries ranged from 70 to 145%.