The rate of CH4 production and, also loss of CO2 and H2 in some research enrichment variants, was determined using a gas chromatograph (GC 3800, Varian, USA) equipped with flame ionization (FID, 200 °C) and thermal conductivity (TCD, 120 °C) detectors in series and with the use of two types of columns: a Poraplot Q 0.53 mm ID (25 m) and a Molecular Sieve 5A 0.53 mm ID (30 m) connected together, were used with helium as the carrier gas [74 (link),80 ]. Methane production rate (MP) was determined on the basis of the linear increase in the methane concentration in time and expressed as a mg of produced CH4 per litre of bottom sediments or enrichment medium per day (mg CH4 L−1 d−1).
Gc 3800
Manufactured by Agilent Technologies
Sourced in United States
The GC 3800 is a gas chromatograph designed for analytical applications. It is capable of separating and analyzing complex mixtures of volatile and semi-volatile compounds. The instrument features automated sample injection and temperature programming to optimize separation and detection.
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8 protocols using gc 3800
1
Methane Production Rate Analysis
2
Quantitative Analysis of Polysaccharide Composition
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25 µL of 4 mM inositol solution were added as internal standard to 500 µL of purified pellicles. Samples were freeze-dried and submitted to 16 h methanolysis at 80°C with 200 µL of 1 M methanolic-HCl. After evaporation of methanol, samples were re-acetylated by addition of 20 µL anhydrous acetic anhydride and 20 µL pyridine. The resulting N-acetyl methyl glycosides (methyl ester) were dried, converted into their trimethylsilyl derivatives and separated by gas chromatography (GC). The gas chromatograph (Varian GC3800, Les Ullis, France) was equipped with a flame ionization detector, a WCOT fused silica capillary column as stationary phase (Varian CP-Sil 5 CB length 25 m, i.d. 0.25 mm, film thickness 0.25 µm) and helium as gas vector (constant pressure 20 psi). The oven temperature program was: 2 min at 120°C, 10°C/min to 160°C, and 1.5°C/min to 220°C and then 20°C/min to 280°C. Sugar quantification was done by integration of peaks and determination of the corresponding molar values using response factors established with standard monosaccharides. Quantity of each carbohydrate is expressed in molar percentage from derivatization of 1 mg of total sugars and results from the analysis of three pellicles from each strain and a technical duplicate.
3
Quantification of Aroma Compounds in Wine
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Major aroma compounds such as isobutanol, isoamyl alcohol, methionol, β-phenylethanol, and acetic acid were determined using a variation of the method published by Ortega et al. (2001 (link)). The strategy followed a liquid-liquid microextraction with dichloromethane and uses several internal standards to correct for matrix effects (recoveries above 95% in all cases). 2-Butanol was used as internal standard for isobutanol, 4-methyl-2-pentanol for isoamyl alcohol, and benzyl alcohol and 4-hydroxy-4-methyl-2-pentanone for methionol, and β-phenylethanol, all of them spiked at 1.5 mg L−1 to the wine. Analyses were carried out using a GC-3800 from Varian (Walnut Creek, CA) equipped with a flame ionization detector (FID). The column used was a DB-WAX from J&W (Folsom, CA) 30 m × 0.32 mm × 0.5 mm film thickness, preceded by a silica precolumn from Agilent Technologies (Santa Clara, CA), 3 m × 0.32 mm i.d. The carrier gas was He at 2.2 mL min−1. Two microliters were injected in split mode (1:20). Injector and detector were both kept at 250°C. The temperature program: 40°C for 5 min, then raised at 4°C min−1 up to 102°C, 2°C min−1 up to 112°C, 3°C min−1 up to 125°C, this temperature was kept for 5 min, 3°C min−1 up to 160°C, 6°C min−1 up to 200°C, and this temperature was kept for 30 min.
4
Photocatalytic Hydrogen Evolution Using ZnS
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A top irradiation vessel connected to a glass-enclosed gas-circulation system was used to evaluate the photocatalytic hydrogen evolution of the ZnS samples. In a typical photocatalytic experiment, 0.5 g sample was suspended in 100 mL aqueous solution containing Na2S·9H2O (0.35 M) and Na2SO3 (0.25 M) as sacrificial agents. The temperature was maintained at 5°C. The visible light source was obtained from a 300 W Xe arc lamp (PLS-SXE 300, Beijing Trusttech Co. Ltd.) equipped with an ultraviolet cutoff filter (λ > 420 nm). The amount of H2 produced was determined with a gas chromatograph (Varian GC-3800) equipped with thermal conductivity detector.
5
Ethylene Quantification in Melons
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The ethylene in the melon cavity was extracted and determined with a Varian GC-3800 gas chromatograph three times. Briefly, 50 μL of a 1 mL gas sample was injected manually by using a micro-syringe (Shanghai Gaoge Industrial and Trading Co., Ltd) into a Varian (GC-3800) equipped with a flame ionization detector (FID) and fitted with a chromatographic column (GDX-102, 3 m × 2 mm i.d., Dalian Institute of Chemical Physics, China). Analyses were run isothermally with an oven temperature of 100 °C, a split/splitless inlet system with a 1041 injector held in splitless mode at 250 °C, and a detector temperature of 120 °C. The injector insert for 0.53 mm i.d. columns was stainless steel (Part No. 392543101, Varian). The samples were separated into a 30 m × 0.32 mm i.d. × 4 μm thickness capillary column (CP8567, CP-silica PLOT, Varian) in splitless mode and maintained at 100 °C. Nitrogen was used as the carrier gas. The flow rates for nitrogen, hydrogen and compressed air were 20, 30 and 300 mL min−1, respectively. Ethylene was quantified by the peak area, and the external standards were used for calibration. The calibration curve was linear when the concentration of ethylene was in the range of 10 to 50%, v/v (μL/L) (r = 0.997) [30 (link)]. Each experiment was performed in triplicate.
6
Soil Methane Oxidation Kinetics
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Ten grams of soils were placed in 60-ml serum vials and closed with butyl rubber septa and caps. Triplicates of each soil sample were incubated at CH4 concentrations of 0.002, 0.5, 1.0, 5.0, and 10.0% (v/v) and temperatures of 10, 20, and 30 °C, up to 90 days. Consumption of CH4 and O2 in the headspace was determined with the gas chromatography technique (GC 3800, Varian, USA) equipped with flame ionization (FID, 200 °C) and thermal conductivity (TCD, 120 °C) detectors in series and with the use of two types of columns: PoraPlot Q 0.53 mm ID (25 m) and a molecular sieve 5A 0.53 mm ID (30 m) connected together. Helium was used as the carrier gas [27 , 35 (link)]. The detector responses were calibrated using series of gas standards: CH4 (Linde, Poland), and O2 (Air Products, Poland) in helium and nitrogen, respectively. The MTA rate was determined on the basis of CH4 reduction in time and calculated as the dry mass of the investigated soils and time (μMol CH4/kg d.w./day). Statistical processing of data (ANOVA, Tukey’s test) was performed using Statistica software [27 , 39 ].
The Q10 temperature coefficient values used to compare the rates of biological reactions or processes were calculated for 10–20 °C and 20–30 °C increments; their average values are presented [40 (link)].
The Q10 temperature coefficient values used to compare the rates of biological reactions or processes were calculated for 10–20 °C and 20–30 °C increments; their average values are presented [40 (link)].
7
Quantifying Dissolved Sulfur Species and Greenhouse Gases
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Sulfate was measured by Ion Chromatography (Dionex-ICS-1000) after filtration with 0.45-μm filters as described previously [59] (link). Total dissolved sulfide (the sum of H 2 S, HS -, and S 2-) was determined by colorimetry using the methylene blue method [60] . Samples for sulfide measurement were not filtered and immediately injected into a 0.5 M NaOH solution to prevent volatilization of sulfide.
The volatile suspended solids (VSS), total suspended solids (TSS), and the dry weight of the sediment were estimated according to the procedure outlined in Standard Methods [61] . Methane and carbon dioxide concentrations in the headspace of the incubations were measured by gas chromatography (GC 3800, VARIAN). The gas chromatograph was equipped with a PORABOND Q column (25 m × 0.53 mm × 10 μm) and a thermal conductivity detector. The carrier gas was helium (15 Psi), the oven temperature was 25 °C, and the gas valve injection was 0.5 ml.
The volatile suspended solids (VSS), total suspended solids (TSS), and the dry weight of the sediment were estimated according to the procedure outlined in Standard Methods [61] . Methane and carbon dioxide concentrations in the headspace of the incubations were measured by gas chromatography (GC 3800, VARIAN). The gas chromatograph was equipped with a PORABOND Q column (25 m × 0.53 mm × 10 μm) and a thermal conductivity detector. The carrier gas was helium (15 Psi), the oven temperature was 25 °C, and the gas valve injection was 0.5 ml.
8
Fungal VOC Profiling for Biomedical Applications
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VOCs produced during fungal growth were collected on tubes containing a TENAX®TA absorbent (Sigma Aldrich). Sampling was active and flow rate was fixed at 10 ml / min during a time sufficient to renew at least three times chamber's volume. Desorption of TENAX®TA tubes was performed at 260 °C for 15 min (ATD 400, Perkin Elmer) and cold entrapment was conditioned at -30 °C. Temperature of transfer line between the ATD and the GC was maintained at 220 °C. VOCs were then injected simultaneously on a VF-5 ms type column (Agilent), they were separated and analyzed with a GC-MS system (GC 3800 coupled with an ion trap, Varian) as described [52, 53] . Analytical conditions were 40 °C for 5 min, 2.5 °C/min up to 170 °C, 7.5 °C/min up to 250 °C and 250 °C for 15 min. Analytes were identified by retention time, compared with a mass spectral library (NIST 2008) and validated with the passage of a standard. VOC production was evaluated on a nutritional media made with an inert material (glass fiber pad CAT N°1823-025 Whatman) in presence of M2 medium. After inoculation of mat+/matheterokaryotic cultures, samples were placed in emission chambers [52, 54] and incubated during ten days, at 27 °C.
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