2.4. Extraction of target analytes from fish homogenates
Detailed descriptions of the target compounds extraction from fish samples and analytical procedures were described in our earlier work (Mottaleb et al., 2009) and similar techniques were followed in this investigation. Briefly, 1.0 ± 0.008 g of individual tissue homogenate was combined with 10 mL acetone in a 20 mL borosilicate glass vial.
Surrogate standard naphthalene d8 (200 ng, 20 lL of 10 ng lL1) was spike from acetone solution to each specimen. Samples were then immediately shaken vigorously and sonicated for 15 min at 25 C using Branson 8150 Sonicator.
Following extraction, samples were transferred into 50 mL polypropylene copolymer conical shaped bottom centrifuge tubes
(Nalgene, Rochester, NY, USA) using 1 mL acetone as a rinse and
centrifuged at 13 000 rpm for 60 min at 4 C. The supernatant
was then transferred into 18 mL disposable, glass test tubes, and
the solvent was evaporated about to dryness under a stream of
nitrogen at 30 C using a Cliper Life Science TarboVap LV. Samples
were subsequently reconstituted in 200 lL of 65:35 (v/v) hexane-acetone for clean-up procedure.
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