Cp ffap cb capillary column

Total SCFA includes acetic acid, propionic acid, butyric acid, and valeric acid. Fecal total SCFA was quantified through methods previously described [18 (link),19 (link)]. The feces collected at Week 6 were extracted using 50% ethanol. Internal standard 2-ethylbutyric acid was also added. After repeated sonication and centrifugation, the supernatant was injected into a gas chromatograph (Shimadzu GC-2010, Tokyo, Japan) with CP-FFAP CB capillary column (Agilent Technologies, CA, USA), and quantified according to the amount of internal standard added.

Fecal SCFAs were analysed using a Shimadzu GC-2010 equipped with a CP-FFAP CB capillary column (Agilent Technologies, CA, USA). Ethanol solution (50%) was used for consecutive sonication and extractions of SCFAs. 2-Ethylbutyric acid was used as the internal standard [29 (link)].

The pH value of the supernatant obtained from in vitro fecal fermentation was determined using a pH meter (Five Easy, METTLER-TOLEDO, Shanghai, China). Short-chain fatty acids were analyzed according to a previous method with minor modifications [31 (link)]. Briefly, the supernatant (0.5 mL) was extracted by acidified 50% ethanol (0.5 mL, pH = 2) with 2-ethylbutyric acid as an internal standard. The mixture was sonicated for 20 min and centrifuged at 4 °C, 9170× g (TGL-16.5M high-speed freezing centrifuge, Shanghai Lu Xiangyi Centrifuge Instrument Co., Ltd., Shanghai, China) for 20 min to obtain the supernatant. Short-chain fatty acids were analyzed on a Shimadzu GC-2010 gas chromatograph (Shimadzu, Kyoto, Japan) with a CP-FFAP-CB capillary column (25 m × 0.32 mm × 0.30 μm, Agilent, Santa Clara, CA, USA). Short-chain fatty acids were determined by the retention times of authentic standards and quantified by the amount of 2-ethylbutyric acid.