Gc 8890

This study used a CRD to compare the supplementation of RUSKEP at 0, 2, 4, 6, 8, and 10% of DM substrates. The diet had a R: C of 70:30, and roughage was obtained by the use of rice straw. Analyses were conducted on the samples to assess the amount of DM, ash, EE, CP [37 ]. The neutral detergent fiber (NDF) and acid detergent fiber (ADF) using a fiber analyzer (ANKOM 200, ANKOM Technology, NY, USA). The GE value of a feed was estimated with bomb calorimetry (Oxygen Bomb Calorimeter; Parr Instrument Company, Moline, IL, USA). The gas chromatography (GC 8890; Agilent Technologies Ltd., Santa Clara County, CA, USA) analysis of fatty acid profiles using the method of Cristie [38 (link)].

At 0, 2, 4, 6, 8, 12, 24, 48, 72, and 96 h, the volume of gas produced was recorded using a 25 mL calibrated glass syringe with an air connector. Four bottles containing only rumen inoculums were included in each run for each sample time, and the average gas production amounts from these bottles were employed as blanks. The net volume of gas was determined by subtracting the blank values from each obtained value. The gas production data were fitted to the model of Ørskov and McDonald [41 (link)] as follows: y = a + b [1 − e^{(− ct)}], where a = the gas production from the immediately soluble fraction, b = the gas production from the insoluble fraction, c = constant rate of gas production for the insoluble fraction, a + b the potential extent of gas production, t = incubation time, and y = gas production at time “t”.
At 24 h of incubation, IVDMD and IVOMD [42 (link)] were evaluated using 24 bottles (4 bottles per treatment, 6 treatments). The pH (FiveGo, Mettler-Toledo GmbH, Greifensee, Switzerland), NH₃-N (Kjeltech Auto 1030 Analyzer, Tecator, Hoganiis, Sweden) [43 ], VFA [44 ], and fatty acid profiles [38 (link)] (GC 8890; Agilent Technologies Ltd., Santa Clara County, CA, USA) of ruminal fluid were evaluated using a second set of 24 bottles (4 bottles per treatment, 6 treatments).

For the analysis of the products, a specific offline-GC FID (Agilent Technologies GC 8890) with an autosampler (50 Position Autoinjector, Agilent Technologies G4567A) was used. The use of a dedicated Dean's switch device is mandatory in order to protect the detector from a methanol overload (as we are systematically working with methanolic solutions). The injection temperature was kept at 180 °C, with a split ratio of 50 : 1. The starting temperature for the oven was 40 °C, which was held for 2 min and then heated at 25 K min⁻¹ to 180 °C, the columns used were a combination of DB-wax ultra inert (30 m, 0.32 mm, 0.5 μm, Agilent Technologies) and a deactivated column after the Dean's switch. A total run time of 7.6 min allowed a fast analysis of liquid samples and gave good separation for methanol, dimethoxymethan, methylformate, formaldehyde, acetaldehyde, acetaldehyde dimethyl acetal and methylacetate. In addition, traces of propionaldehyde dimethyl acetal and propionaldehyde diethyl acetal were observed but not quantified. Fischer–Tropsch products could not be measured. Details about process analytics have been published elsewhere.³⁶

Seawater methane concentrations were measured using a cryogenic purge-and-trap system connected to an Agilent GC-8890 gas chromatography with a flame ionization detector¹⁵ . Briefly, 50 mL seawater was introduced into a glass chamber and purged with high-pure N₂ at a flow rate of 80 mL min⁻¹ for 5 min. The extracted gas was trapped in a U-shape stainless steel trap packed with Porapak Q (80/100 mesh) and immersed in liquid nitrogen. After purging, the Porapak Q trap was transferred to a boiling water bath and trapped methane gas was released into the GC. Methane samples during incubation experiments were analyzed using the headspace method, followed by gas chromatography^{47 (link)}. Calibration was conducted with different concentrations of certified methane standards (National Institute of Metrology, China). Nutrient concentrations were determined with spectrophotometric methods using an autoanalyzer (SEAL AA3)⁴⁸ .

Dry Arabidopsis seeds (0.15 g), pulverized in liquid nitrogen and FA methyl esters (FAMEs), were prepared according to the method by Li et al. (Li et al., 2015 (link)). FAMEs were analyzed using a GC8890 instrument (Agilent, Santa Clara, CA, USA) and a 30 m × 0.25 mm DB-23 column with a nitrogen carrier. The gas chromatography (GC) procedure used the following parameters: split ratio 10:1, initial column temperature held at 100°C for 2 min, then raised to 230°C at the rate of 15°C min⁻¹ with the final temperature held for 5 min; injection port temperature 230°C; transfer line temperature 250°C; ion source temperature 230 °C; speed of carrier gas 1.0 ml min⁻¹; and injection volume 1 μL. Methyl heptadecanoate was used as an internal standard, and a standard curve method was used as the quantitative approach to identify FAMEs (Yin et al., 2018 (link)).

On the 42nd day of each trial period, approximately 10 mL of blood was collected by jugular puncture before morning feeding. Blood samples were immediately placed on ice after collection and then centrifuged at 3000× g for 15 min at 4 °C. Subsequently, the obtained plasma was immediately transferred to a polypropylene bottle and stored at −20 °C for further analysis.
Biochemical blood indicators included glucose (GLU), triglyceride (TG), non-esterified fatty acids (NEFA), and β-hydroxybutyrate (BHB), which were determined by an automatic biochemistry analyzer (Cobas c311, Roche, Basel, Switzerland) according to the instrument’s instructions. Propionate contents of blood were analyzed (GC 8890; Agilent Technologies Ltd., Palo Alto, CA, USA). Furthermore, the levels of acetyl-CoA (A-CoA, H331), citrate synthase (CS, A108), glucose-6-phosphatase (G-6-Pase, H580), pyruvate kinase (PK, A076), insulin (INS, H203), growth hormone (GH, H091), glucocorticoid (GC, H094), triiodothyronine (T3, H222), and tetraiodothyronine (T4, H223) in the plasma were assessed using commercial ELISA kits (Nanjing Jiancheng Bioengineering Institute, Nanjing, China) according to the manufacturer’s instructions, respectively. The ELISA results were obtained using a microplate reader (Varioskan LUX, ThermoFisher Scientific, Waltham, MA, USA).