Fecal Lipid Extraction and GC Analysis

0.1 g feces sample was weight and mixed with 1 mL methanol. After vortexing, ultrasonic treatment and centrifugation, the supernatant was transferred into a new tube. The pellet was further extracted with 1 mL methanol. The supernatant from the two extractions were combined and dried. Then 800 µL 0.5 mmol KOH‐methanol was added, shaked to dissolve and incubated in the dark for 1 h. 800 µL n‐hexane was further added and mixed for 1 min, and then incubated to separate layers. The upper layer of n‐hexane was transfer to a new tube, extract for 3 times. The n‐hexane phases were combined, dried and dissolved in n‐hexane, which was further analyzed using the Agilent 6890N gas chromatograph equipped with PEG‐20 M cross‐linked polyethylene glycol column.