6890n network gas chromatograph

All extract samples were analyzed for total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) using an Agilent 6890N Network gas chromatograph (GC) equipped with a flame ionization detector (FID). The TPH content, covering a range of C10–C40, was determined in water and sediment samples following the US EPA 8015C standard method. The analysis of target PAHs, specifically the 16 U.S. EPA-regulated PAHs and seven deuterated PAHs, in water and sediment samples, followed the US EPA 8270D standard method. Consequently, GC and FID operating conditions were modified for TPH and PAH analyses based on the standard method being applied to the extracts (i.e. 8015C or 8270D). The following section describes the general operating conditions. Helium was used as the carrier gas, and the analysis was performed using an HP-5 column (30 m × 0.32 mm × 0.25 μm). The detector temperature was set at 350 °C, with a hydrogen gas flow rate at 35 mL/min, air flow rate at 350 mL/min and helium gas flow rate at 20 mL/min. The inlet operated with an electronic pneumatic capture splitless make, with a temperature of 275 °C, pressure of 14.8 psi, split flow rate of 6.8 mL/min and total flow rate of 25.8 mL/min. The oven temperature ranged from 65 to 325 °C, with a run time of approximately 53.5 min, pressure set at 14.8 psi and a flow rate of 3.3 mL/min.

The analysis was performed on an Agilent 6890N Network Gas Chromatograph combined with an Agilent 5973 Mass Selective Detector and equipped with a silica fused capillary column DB-5MS (30 m × 0.25 mm i.d., film thickness 0.25 μm; Agilent Technologies, Santa Clara, CA, USA). The oven temperature was programmed from 80 °C to 270 °C at a rate of 10 °C/min. The flow rate of the carrier gas (helium) was 0.6 mL/min. The injector and the interface (between GC and MS) were kept at 250 °C. The samples of the dry extracts (PE and CHE, 10 mg/mL) and standards (1 mg/mL) were dissolved in toluene and derivatized with BSTFA+TMCS (100 μL) for 3 h in the dark. After this time the samples were injected (1 μL) into the GC-MS system. Identification of the compounds was performed on the basis of their chromatographic behavior (retention times) and MS-spectra in comparison with the standards (both retention times and MS-data) and W9N08.L and NIST 05.L library databases (MS-fragmentation). In all cases when the standards were unavailable, the quality of the library matches ranged from 90% to 99%.

GC–MS analyses were performed using a 6890N Network Gas Chromatograph linked to a 5973 Network mass selective detector (Agilent, Santa Clara, CA, USA) with He as the carrier gas. Permethylated alditol acetates were injected onto a fused silica HP-5MS capillary column (30 m × 0.25 mm × 0.25 µm). Chromatographic conditions: injector temperature—220 °C; injection volume—1 µl; temperature of the ion-source—230 °C and temperature of the quadrupole—150 °C; acquiring mode—scan, from m/z 40 to m/z 500. Alditol acetates were analysed using the following temperature programme: 100 °C, held for 2 min, 100 to 180 °C at 10 °C min⁻¹, held for 2 min, 180 °C to 190 °C at 1 °C min⁻¹, held for 4 min, 190 °C to 240 °C at 10 °C min⁻¹, held for 5 min, then to 280 °C at 20 °C min⁻¹, held for 5 min. PMAA were analysed with the temperature programme: 80–120 °C at 5 °C min⁻¹, held for 1 min; 120–230 °C at 3 °C min⁻¹, held for 1 min; to 280 °C at 20 °C min⁻¹, held for 5 min.

The analyses were carried out on an Agilent GC/MS system consisting of a 6890 N Network gas chromatograph and a 5973 Network Mass Selective Detector (5973N MSD) operating in 70-eV electron impact ionization mode. Mass spectra were acquired in full- scan mode in the range of 40–650 m/z. The GC was equipped with a 30-m HP-5MS capillary column (0.25-mm i.d., 0.25-mm film thickness), and helium was used as the carrier gas at a rate of 1 mL/min. The injector was set at 250 °C and was used in the split mode. The oven temperature program was set at an initial temperature of 70 °C (hold time 1.5 min), then a temperature ramp of 10 °C/min up to 280 °C was used to reach a final temperature of 280 °C (final hold time 20 min). The compounds were tentatively identified based on their Electron Ionization (EI) mass spectra using the NIST08 database.