7820 gc system

Feces were weighed, homogenized in 10% ethanol, and spun at 14,000g for 5 minutes. Supernatant was sent to UCSD’s Glycoanalytics Core. There, Samples were centrifuged at 10,000g for 5 minutes and spin filtered using prewashed 3K spin filtration unit (Centrifugal device, Pall, Life Sciences, Part No. OD003C34). Flow through was spiked with 1.0μg of Inositol as internal standard and lyophilized. Dried material was reduced using sodium borohydride in presence of 1M ammonium hydroxide, overnight at room temperature. Excess reducing agent was neutralized on ice bath using 30% aqueous acetic acid solution. Samples were then dried by nitrogen flush and co-evaporated with 9:1 methanol: acetic acid mixture (3 times) followed by anhydrous methanol (3 times). Finally, the samples were acetylated using mixture of pyridine and acetic anhydride (1:1 v/v) and alditol acetylate of monosaccharides were analyzed by GCMS (Agilent Technologies, 7820 GC System attached with 5975-MSD). Restek-5ms column (30m x 0.25mm x 0.25μm) was used for profiling of the monosaccharides, Ultrapure He was used as carrier gas in split less mode at a flow rate of 1.2mL/min. Quantification of monosaccharides were done based on the response factors obtained from known amount of standard mixture.

The concentrations of SCFAs were detected by gas chromatography [9 ]. For this, 25% metaphosphoric acid (100 mL) was mixed with a serum sample (200 mL) to remove the solid particles. After centrifugation, 4 mL of crotonic acid was added to the supernatants (200 mL), and the mixture was vortexed and then filtered. The SCFAs was separated and detected by gas chromatography spectrometry (Agilent Technologies 7820 GC system).

A PANalytical’s Empyrean diffractometer was employed to conduct X-ray diffraction (XRD) measurements. Fourier transformed infrared (FTIR) spectra were collected on a Thermo Scientific Nicolet iN 10Mx infrared microscope. UV–Vis spectra were recorded on a Cary 100 spectrophotometer equipped with a diffuse reflectance accessory (DRA). An Edinburgh FI/FSTCSPC 920 fluorimeter was used to collect photoluminescence (PL) spectra. The morphologies of the samples were characterized using a scanning electron microscope (SEM, JEOL JSM-7400F equipped with a FEG source) operated at 3.5 kV using a secondary electrons detector. X-ray photoelectron spectroscopy (XPS) measurements were conducted on a Thermo Fisher Scientific ESCALAB 250 using monochromated Kα X-rays (1486.6 eV), and all the binding energies obtained in XPS spectra were calibrated using the C 1s peak at 284.6 eV. N₂ (99.999%) adsorption-desorption measurements were performed using a Quantachrome autosorb IQ2 at 77 K. The specific surface area was calculated using the Brunauer–Emmet–Teller (BET) model. Pore‐size distribution was calculated using non‐localized density functional theory (NLDFT) from the nitrogen sorption measurements. The amount of generated gases in the cell of the PEC set up were analyzed using a gas chromatograph (Agilent 7820 GC system) equipped with a thermal conductivity detector (TCD).