Agilent 7890b system

Short-chain fatty acid concentrations in ileal digesta were measured by gas chromatography as a described method in our previous study [30 (link)]. Briefly, the mixture of 0.4 ± 0.01 g of ileal digesta and 1.6 mL of sterile double distilled water was centrifuged (13,000 × g) for 10 min at 4 °C. Transferred 1 mL of supernatant to a new tube and mixed with 0.2 mL of 25% (w/v) metaphosphoric acid. The thoroughly mixed samples were stored at – 20 °C for 12 h to precipitate proteins. After thawing, the samples were centrifuged at 13,000 × g for 10 min to obtain supernatants. Then the supernatants were filtered with 0.22 µm syringe filters and analyzed on an Agilent 7890B system (Agilent, Palo Alto, CA, USA). The lactate concentration in the ileal digesta was determined with the enzymatic colorimetric method according to the instructions of the Lactate Assay Kit (Jiancheng Bio Ins., Nanjing, Jiangsu, China). Absorbance was measured at 570 nm using the Olympus AU2700 auto analyzer (Olympus, Tokyo, Japan). All analyses were performed in triplicate to calculate the average.

25 μL of
plasma was mixed with 25 μL of the internal standard (deuterated
capric acid, 2.5 μg/mL) in acetonitrile and 50 μL of 2,2-dimethoxypropane
and vortexed. 75 μL of a 1.3 M boron trifluoride-methanol solution
was added and incubated at 50 °C for 30 min. 400 μL of n-hexane was added and vortexed to homogenize. 250 μL
of the upper organic phase was transferred to a vial with a silanized
glass insert and analyzed by gas chromatography with mass spectrometric
detection (GC MS/MS) on an Agilent 7890B system (Agilent Technologies,
Paolo Alto, CA, USA) coupled to an Agilent triple quad mass spectrometer
7000C equipped with an electron ionization source. Separation was
achieved over a DB-FFAP column, 30 m × 250 μm i.d. (J&W
Scientific, Folsom, CA, USA). Helium was used as carrier gas at a
constant flow of 1.4 mL/min. The injection volume was 1 μL.
The initial oven temperature was set to 60 °C for 0.5 min and
thereafter increased to 170 °C at a rate of 20 °C/min, after
which the temperature was increased to 250 °C at a rate of 50
°C/min and held for 0.5 min. The total run time was 8.1 min.
The lower limit of quantification of the assay was 0.5 μg/mL.

Metabolite profiling of soybean n-heptane and NaHDES extracts (10 mg/ml) was performed using a 7890B Agilent system (Agilent Technologies, United States) coupled to a quadrupole time-of-flight (QToF) 7200 (Agilent Technologies, United States) equipped with an electronic ionization (EI) interface. Separations were achieved in a 30 m × 250μm × 0.25μm DB5- MS + 10 m Duragard Capillary Column (Zorbax, Agilent Technologies, United States). The samples were diluted at 1:10 in n-heptane and filtered with a 0.22-μm nylon syringe filter before injection. The injection volume was 1μl using a split flow of 8.4 ml/min. The helium flow rate was 0.8 ml/min. The injector temperature was 250^°C. Oven temperature started at 60^°C (1 min), followed by 325^°C at the rate of 10^°C°/min (10 min) and 11-min solvent delay. Metabolites present in the n-heptane and eucalyptol/menthol (1:1) extracts were annotated using the match of mass spectra in the Agilent Mass Hunter Unknown Analysis tool and mass spectral databases (i.e., NIST MS Search v.2.0 and Fiehn Lib).