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ARTICLE IN PRESS

S. Orecchio et al. / Environmental Research 107 (2008) 371–379 373

Fig. 1. Sampling sites.

Fig. 2. Sampling sites.

Among the different techniques and various solvents tested, we used 3. PAH analysis
Soxhlet extraction because it allowed us to obtain the highest recovery percentage
of PAHs. The qualitative and quantitative determinations were carried
All samples were extracted in Soxhlet extractor for 24 h using 200 ml of
dichloromethane. The extracted fractions were filtered through pre- out by means a gas chromatograph (Shimadzu mod. GC-17A)
cleaned Pasteur pipette filled with solvent-rinsed glass wool and pre-cleaned coupled to a mass spectrometer (Shimadzu, quadrupole detector
anhydrous Na 2 SO 4 , rinsed and concentrated in a rotary evaporator at mod. GCMS-QP5000), operating with acquisition data (Shimadzu,
T ¼ 3570.5 1C. The final volume was around 10 ml. Finally, the solution containing CLASS 5000 system). GC separations were achieved on an Equity-5
PAHs was dried under a weak nitrogen flow. The dry residue was dissolved in
0.5 ml solution containing the following perdeuterated internal standards in (30 m 0.25 id, 0.5 mm) fused-silica capillary column supplied by
Supelco (Milano, Italy). The injector mode was splitless (0.6 min)
cyclohexane (0.2 mg/l each): acenaphthene d 10, phenanthrene d 10 , chrysene d 12
and perylene d 12 . and a total flow 20.6 ml/min was used. The injection of both