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All samples were
stored in clean aluminium foil and send to the laboratory in a cool box, then
stored at ?20 °C until further analysis. In the laboratory, samples
were freeze-dried (72 h) sieved using 63 ?m mesh to eliminate
of paticle size effect. For analysis, 100 ?L of PAH surrogate internal standard
mixture (200 ng g?1 of each component, naphthalene-d8, anthracene-d10,
perylened12 and chrysene-d12) was added to about 5 g of freeze-dried sediment for quality control of PAH analyses. Then extraction
of PAHs were carried out with Soxhlet for 10 h into 100 mL of dichloromethane. For
deletion of sulfure, added active copper to this dilution and store in refrigerator
(4 c) for 24 h. Then the extracts were reduced to approximately 4–5 ml by
rotary evaporation, and then transferred to the top of a 5%H2O deactivated
silica gel column chromatography (1 cm i.d. 9 cm) to eradicate the polar
compounds. The PAH fraction was eluted with 20 mL of dichloromethane/hexane
(1:3, v/v). The eluent after solvent lessening was further Fractionated using
fully activated silica gel column chromatography and eluted with 14 ml
dichloromethane/hexane (1:3, v/v) to get the PAH fraction. Alkanes were eluted
with 4 ml of hexane former of PAHs for other research. Then they were
concentrated under a gentle stream of nitrogen blow down and reconstituted in a
volume of 100 ?L. P-terphenyl-d14 as PAH internal standard was added
immediately prior to being injected into the GC–MS (Harris et al., 2011; Yunker
and Macdonald, 2003). All of the reliable PAH standards were procured from Sigma
Aldrich. PAH analyses were  accomplished by an Agilent Technologies 5975C quadrupole mass
spectrometer coupled with an Agilent 7890A gas chromatograph equipped with a
fused silica capillary DB-5MS column (30 m _ 0.25 mmi.d., 0.25 lmfilmthickness.
Helium gas was routined as a carrier. For PAH analysis, the oven temperature
program was set up as follows: initial temperature 70 °C for 2 min, heated to
150 °C at 30 °C/min and then to 310 °C at 4 °C/min, and held for 10 min
resulting in a 60.3 min; and for analysis of n-alkanes: it started at 70 °C,
held for 2 min, increased at 30 °C/min to 150 °C, and finally, increased at 4
°C/ min to 290 °C, held for 10 min. Thirteen PAHs were analyzed including
Naphthalene (Nap), 2M-Naphtalene

1M-Naphtalene (1M.Nap), 2,6DM-Naphtalene(2.6DM-Nap),

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-3Methylphenanthrene(3M-Phe), 2-Methylphenanthrene(2MPhe),



M-Pyrene(1M.Pyr), Benzo(a)anthracene(BaA),


pyrene(BeP), Benzo (a) pyrene(BaP), Perylene (Pery), Indeno

(InP), Dibenzoa,hanthracene (DahA), Benzoghiperylene(

BghiP). recovery
efficiencies were calculated by 4 surrogate compounds that average of these
analyses were 94 ± 18% in all samples and cast-off for the recovery
correction calculations. The
Limit of Detection, or LODs and Limit of Quantification or LOQs for

each 30PAHs were calculated
as the concentrations at which the signal to-

noise ratios correspondingly
were 4 and 9.

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