J w gc

Short-chain fatty acids (SCFA) were identified and quantified via gas chromatography with a flame ionization detector in a GC 2010 chromatograph of the brand Shimatzu^® (Toyko, Japan), using the method reported by Pietro-Femia et al. [32 (link)] with some modifications. To 250 µL of the sample from the colon digestion process, 25 µL of phosphoric acid solution (5 M) and 250 µL diethyl ether were added. The mixture was homogenized and subsequently centrifuged at 13,000 rpm for 3 min (analyte recovery average of 80%). The ether phase was injected directly onto a column HP-FFAPP (30 m × 0.250 mm × 0.25 µm, columns Agilent JW GC) at 180 °C, using N₂ as a carrier gas, and the flow was 1 mL min; the run time for each analysis was 15 min, and the temperature of the detector was fixed at 230 °C. Quantification was carried out using calibration curves of acetic (R² = 0.9979), propionic (R² = 0.9993), and butyric (R² = 0.9975) diluted in water to a concentration range of 40, 20, 15, 10, 5, 2.5, 1.25, and 0.75 µM/L [32 (link)].

The samples and standards were then placed in a GC-MS (GC-MS-QP2010 Ultra fitted with an AOC-20s Shimadzu auto sampler and a Shimadzu AOC-20i auto injector) with a polar column (Agilent J&W GC, 30m, 0.250 diam (mm), film 0.25 (μm) temperature limits form 40°C to 260°C). SCFA was determined by injecting 1 μl of sample at 250°C with helium (1.97 ml/min) as the carrier gas with a 5.0 split injection mode. Pressure was maintained at 143.3 kPa and helium flow of 103.4 ml/min. The mass spectrometer operated in the electron ionization mode at 0.2kV, the source temperature was 220°C with scan mode between 33 to 150m/z.
CAR was detected by injecting 1 μl of sample at 250°C with helium (1.7 ml/min, 5.0) as the carrier gas with a 50.0 split injection mode. Pressure was maintained at 161.1 kPa and helium flow of 89.7 ml/min. The mass spectrometer operated in the electron ionization mode at 0.2 kV, the source temperature was 230°C with scan mode between 33 to 280 m/z. Total program time was 5.88 min. The National Institute of Standards and Technology (NIST) library was used to identify and match peaks.