6890 gas chromatograph

Natural seawater (salinity of 31.6 and pH of 7.8) was collected from the black rock reef area, Dalian, China (31.87°N, 121.55°E). The seawater was filtered with a 0.45 μm polycarbonate filter to remove large particles.
Sandy sediments used in the experiments were collected in the intertidal zone of the Yellow River mouth, Dongying, China (37.73°N, 119.16°E). After collection, the sediments were dried and passed through a sieve to separate particles by size (<200 μm).
Three kind of Bohai crude oils were employed in this study, which were obtained from the Liaohe oilfield (LX), Bohai south regional oilfield (YYH) and Bohai central regional oilfield (YYS), respectively. These oils were chosen due to their significant differences in viscosity and asphaltene content. Physicochemical properties of the three test oils are listed in Table 1, and the resolved n-alkanes of the test oils are plotted in Fig. 1. The oil hydrocarbon distributions were measured using an Agilent 6890 Gas Chromatograph equipped with a Flame-Ionization Detector (GC-FID). Parameters of GC-FID analysis were described in Wang et al. (2019),^{16 (link)} and the distribution of n-alkanes were resolved using a certified reference material (C₈–C₄₀ alkane mixture, Sigma-Aldrich). The resolved n-alkanes of the test oils are distributed in the C₈ to C₃₂ carbon range with the maxima being around C₂₀ to C₃₀.

Analysis of fecal metabolomic profiles was performed by a commercial laboratory (Metabolon, Morrisville, NC) as previously described.⁴⁹ SCFAs were separated from fecal matter by liquid-liquid extraction under basic conditions with inclusion of an internal standard. Extracts were clarified by centrifugation and then acidified in the presence of methyl-t-butyl ether (MTBE). MTBE layers were separated by centrifugation, and SCFAs were resolved by capillary gas chromatography with flame ionization detection (Agilent 6890 Gas Chromatograph).

Before reaction, the catalysts were activated at 80 °C under vacuum overnight. Glass reaction vials were loaded with the catalyst (50 mol% Zn), phenylacetylene (0.5 mmol), 4-isopropylaniline (1 mmol), tetradecane (1 mmol) as internal standard and dry toluene (1 mL) as solvent. The vials were then placed in an aluminum block at 110 °C and stirred at 500 rpm using a magnetic stirring bar. After reaction, the catalyst was recovered by centrifugation and the liquid supernatant was analyzed by GC (Shimadzu 2014 GC equipped with a FID detector and a CP-Sil 5 CB column) and GC-MS (Agilent 6890 gas chromatograph, equipped with a HP-5MS column, coupled to a 5973 MSD mass spectrometer). After the reaction, the catalyst was dried under vacuum and characterized by PXRD. Recycling tests were performed after re-activation of the sample for 16 h before each run. The turnover frequency (TOF) of the Zn sites was calculated as mol of hydroamination product formed per mol of Zn per hour.

All samples were analysed with MxP Global Profiling and MxP Lipids. MxP Global Profiling was performed employing (1) gas chromatography-mass spectrometry (GC-MS) using an Agilent 6890 gas chromatograph coupled to an Agilent 5973 mass-selective detector and (2) liquid chromatography‐tandem mass spectrometry (LC-MS/MS) using an Agilent 1100 high‐performance liquid chromatography system coupled to an Applied Biosystems API 4000 triple quadrupole mass spectrometer, as has been described in detail before.21–23 (link)
Up to 1449 metabolites were detected within the studies depending on the sample matrix and the analytical technique. The metabolites originated from 10 different ontology classes and comprised 838 known metabolites and 611 unknown spectral features. Only those metabolites that met specific quality criteria as described in24 (link) were included in further statistical analyses. Furthermore, quality assessment of plasma samples was performed using the MxP Biofluids Quality Control assay (see our patent application WO2015145387A1).25