Method for extracting and identifying polysaccharide from complex sample

A method for extracting and identifying a polysaccharide from a complex sample, comprising the following steps:

• subjecting a complex sample to be treated to sterilization and enzyme deactivation to obtain a system, and subjecting the system to solid-liquid separation to obtain a sterilization and enzyme deactivation-treated solution, the complex sample to be treated being selected from the group consisting of feces, a fermentation broth, and a medium;
• deproteinizing the sterilization and enzyme deactivation-treated solution to obtain a deproteinized solution;
• purifying the deproteinized solution by using a hydrophilic lipophilic balance-solid phase extraction (HLB-SPE) cartridge to obtain a purified solution;
• subjecting the purified solution to alcohol precipitation to obtain the polysaccharide;
• and
• subjecting the polysaccharide to methylation, glycoside residue derivatization and liquid chromatography-mass spectrometry (LC-MS) analysis in sequence.