Db 5ms fused silica capillary column

Around 100–200g dried and crushed samples (<100 mesh) were Soxhlet extracted for 72 h by the solvent mixture of dichloromethane (DCM) and methanol (93:7, v:v). After removing the solvents and asphaltenes by n-hexane, the resultant soluble fraction was separated into aliphatic hydrocarbons, aromatic hydrocarbons, and polar compounds by using the column chromatography method (alumina/silica gel column). Aliphatic hydrocarbons, aromatic hydrocarbons, and nonhydrocarbons were extracted by washing with n-hexane, dichloromethane, and methanol, respectively.
Aliphatic hydrocarbons were analyzed using a Gas Chromatography–Quadrupole Mass Spectrometer (GC–MS) 6890N/5973N (Agilent Technologies, Palo Alto, CA, USA), which was fitted with a DB-5 MS fused silica capillary column (J&W Scientific, Agilent, USA; 30 m × 0.25 mm × 0.25 µm). The GC oven temperature was initially set at 80 °C (hold for 5 min), then programmed to 290 °C (hold for 40 min) at a rate of 4 °C/min. The compounds were identified by comparing their mass spectra with those in the NIST02 library and published data.
The biomarker experiments were conducted in the sample pretreatment laboratory of the Key Laboratory of Petroleum Resource Research, Northwest Institute of Eco-Environment & Resources, Chinese Academy of Sciences.

A sample of the water column was taken for WAF and CEWAF at the beginning (0 h) and at the end (96 h) of the experiment. Total hydrocarbons, aliphatic (C₁₀ - C₄₀) and PAHs, including 16 US EPA priority PAHs were quantified in WAF and CEWAF following the method of Wang et al. (48 (link)). Prior to extraction, samples were enriched with 100 μl of the following standards: biphenyl d10, phenanthrene d10, chrysene d12, benzo(a)pyrene d12 (10 mg/mL), and o-terphenil (200 mg/mL). In each set of samples, a technical blank and a duplicate sample were added. Identification and quantification of the compounds was carried out with standards from Ultra Scientific® in the case of the PAHs and from Chiron^© for deuterated PAHs. Total hydrocarbons were analyzed with an Agilent 7890A^© gas chromatograph equipped with an FID detector. PAHs were analyzed with a Perkin-Elmer^© gas chromatograph equipped with a Clarus 500® mass-selective detector using a 30 m × 0.25 mm (i.d.) x 0.25 DB-5 MS fused silica capillary column (J & W Scientific^©), operating in the selected ion monitoring (SIM) mode, calibrations were verified daily, and the calibration curves were carried out for each set of samples.

GC–MS analysis was performed on an Agilent 7890/5975C GC–MS (Agilent Technologies, Santa Clara, CA, USA). FAs were separated using a 30 m × 0.25 mm × 0.25 μm DB-5 MS fused silica capillary column (J&W Scientific, Folsom, CA, USA). The sample injection volume was 1 μL with a split ratio of 10:1. Helium (99.9996%) was used as the carrier gas and the flow rate was 1.2 mL/min. The injector and transfer line temperatures were both 280°C. The oven temperature program was: 60°C for 1 min, then ramped to 200°C at 20°C/min, and held for 3 min; later, ramped to 280°C at 5°C/min, and held for 5 min. The metabolic data were collected at the mass scan range from 50 to 500 amu after a solvent delay of 3.5 min. All samples were analyzed in a random order.
In order to monitor the repeatability of sample analysis, quality control (QC) samples were added into the analysis sequence for every 3 samples. QC samples were prepared by equally mixing the tested serum samples, and processed together with samples.