All from Sigma Aldrich. PAH analyses were accomplished by

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Last updated: June 21, 2019

All samples werestored in clean aluminium foil and send to the laboratory in a cool box, thenstored at ?20 °C until further analysis.

In the laboratory, sampleswere freeze-dried (72 h) sieved using 63 ?m mesh to eliminateof paticle size effect. For analysis, 100 ?L of PAH surrogate internal standardmixture (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 extractionof PAHs were carried out with Soxhlet for 10 h into 100 mL of dichloromethane.

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Fordeletion 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 byrotary evaporation, and then transferred to the top of a 5%H2O deactivatedsilica gel column chromatography (1 cm i.d. 9 cm) to eradicate the polarcompounds. The PAH fraction was eluted with 20 mL of dichloromethane/hexane(1:3, v/v).

The eluent after solvent lessening was further Fractionated usingfully activated silica gel column chromatography and eluted with 14 mldichloromethane/hexane (1:3, v/v) to get the PAH fraction. Alkanes were elutedwith 4 ml of hexane former of PAHs for other research. Then they wereconcentrated under a gentle stream of nitrogen blow down and reconstituted in avolume of 100 ?L.

P-terphenyl-d14 as PAH internal standard was addedimmediately prior to being injected into the GC–MS (Harris et al., 2011; Yunkerand Macdonald, 2003). All of the reliable PAH standards were procured from SigmaAldrich. PAH analyses were  accomplished by an Agilent Technologies 5975C quadrupole massspectrometer coupled with an Agilent 7890A gas chromatograph equipped with afused 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 temperatureprogram was set up as follows: initial temperature 70 °C for 2 min, heated to150 °C at 30 °C/min and then to 310 °C at 4 °C/min, and held for 10 minresulting 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 includingNaphthalene (Nap), 2M-Naphtalene(2M-Nap),1M-Naphtalene (1M.Nap), 2,6DM-Naphtalene(2.6DM-Nap),Acenaphthylene(Acy),Acenaphthene(Ace),2,3,5TM-Nap(2.3.5TM.Nap),Fluorene(Flo),Dibenzothiophene(DibZ),Phenanthrene(Phe),Anthracene(Ant),-3Methylphenanthrene(3M-Phe), 2-Methylphenanthrene(2MPhe),9-Methylohenanthracene(9M-Phe),1Methylphenanthrene(1MPhe),3,6DM-Phenanthrene(3.6DM.Phe),Fluoranthene(Flu),Pyrene(Pyr),Benzo(a)fluorine(BaF),M-Pyrene(1M.

Pyr), Benzo(a)anthracene(BaA),Chrysene(Chr),Benzo(b)fluoranthene(BbF),Benzokfluoranthene(BkF),Benzo(e)pyrene(BeP), Benzo (a) pyrene(BaP), Perylene (Pery), Indeno1,2,3-cdpyrene(InP), Dibenzoa,hanthracene (DahA), Benzoghiperylene(BghiP). recoveryefficiencies were calculated by 4 surrogate compounds that average of theseanalyses were 94 ± 18% in all samples and cast-off for the recoverycorrection calculations. TheLimit of Detection, or LODs and Limit of Quantification or LOQs foreach 30PAHs were calculatedas the concentrations at which the signal to-noise ratios correspondinglywere 4 and 9.

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