5975c inert msd quadrupole mass spectrometer

An Agilent Technologies 7890A gas chromatography system coupled to an Agilent Technologies 5975c inert MSD quadrupole mass spectrometer (Agilent Technologies, Germany) and equipped with an Agilent Technologies 7697A Headspace automatic injector (Agilent Technologies, Germany) and an DB-FFAP capillary column (30 m × 0.25 mm i.d., 0.25 μm film thickness, Agilent Technologies, Germany) was used to perform an analysis of SCFAs from fecal samples. The headspace was maintained at 80°C with an incubation time of 30 min. The samples (1 mL) were injected in a splitless mode into the column at a temperature of 80°C. Helium was used as the carrier gas at a constant flow rate of 1 mL/min through the column. The initial oven temperature was 50°C, which was maintained for 1 min and then raised to 200°C at a rate of 10°C/min. The temperatures of the ion source and injector were 250°C. The mass detector system was operated in an electron impact (EI) mode with an ionization energy of 70 eV. The data of ions monitored were collected from m/z 33 to 200. A qualitative analysis was performed by the National Institute of Standards and Technology (NIST 11) MS library.

GC-MS analysis was carried out on an Agilent 7890A gas chromatograph coupled to an Agilent 5975C inert MSD quadrupole mass spectrometer. The GC was equipped with a HP-5MS column (0.25mm x 30m x 0.25μm, Agilent, Santa Clara, CA) with helium as the carrier gas. Interface and ion source temperatures were both 230°C. Amino acids were analyzed with a split-less 1μl injection. Oven temperature was initially held at 135°C for 3 minutes followed by a ramp of 2.5°C/minute up to a temperature of 280°C for 2 minutes. Sugars in cell wall hydrolysate and starch samples were analyzed with a 1μl injection 10:1 split ratio. The oven temperature was initially held at 150°C for 1 minute followed by a ramp of 5°C/minute up to a temperature of 175°C followed by a ramp of 3°C /minute up to a temperature of 240°C where it was held for 2 minutes followed by a final ramp of 10°C /minute up to 250°C. Fatty acids were analyzed with a split-less 1μl injection. Oven temperature was initially held at 80°C for 3 minutes followed by a 30°C/min ramp up to 200°C where it was held for 2 minutes followed by another ramp of 6°C/min up to 305°C. Labeling patterns of metabolites, amino acids, fatty acids and sugars used in the model are given in the supplementary material, S3–S7 Tables.

The short-chain fatty acid (SCFA) analysis was used by a 7890A gas chromatography system (Agilent Technologies, Germany) coupled to a 5975c inert MSD quadrupole mass spectrometer, a 7697A headspace automatic injector, and a DB-FFAP capillary column (30 mm × 0.25 mm i.d., 0.25 μm film thickness). A portion of the 0.1 g homogenized fecal sample was mixed in 1 mL of 6% H₃PO₄ solution by ultrasound for 3 min and was then placed in an automatic headspace sampler at 80°C for 30 min. Subsequently, the samples (1 ml) were injected into the column at 80°C. Helium gas was used as a carrier for samples to pass through the column at a constant flow rate of 1 mL/min. The oven was preheated at 50°C for 1 min; then heated up to 200°C at the rate of 10°C/min. The temperature of the ion source and injector was set to 250°C. The mass detector system was operated in an electron impact (EI) mode with ionization energy of 70 eV. The data of ions monitored were collected from m/z 33 to 200. The short-chain fatty acids were quantified by the MS library of the National Institute of Standards and Technology (NIST 11).