LC-MS metabolomics detection
Metabolites of fecal samples were detected in positive and negative ion mode, and metabolites were separated using a Waters Acquity 1-Class PLUS ultraperformance liquid chromatography system (Waters XevoG2-XS QTOF high-resolution mass spectrometer). Primary and secondary mass spectrometry data were collected in MSe mode under the control of acquisition software (MassLynx V4.2, Waters). In each data acquisition cycle, dual-channel data acquisition can be performed at both low and high collision energies simultaneously. The low collision energy is 2 V, the high collision energy range is 10~40 V, and the scI ion source is as follows: capillary voltage, 2000 V (positive ion mode) or -1500 V (negative ion mode); cone voltage, 30 V; ion source temperature, 150 °C; desolvent gas temperature, 50 °C; backflush gas flow rate, 50 L/h; desolventizing gas flow rate, 800 L/h (Wang et al., 2020).
The raw data collected using MassLynx V4.2 was processed by Progenesis QI software for peak extraction, peak alignment, and other data processing operations, based on the Progenesis QI software online METLIN database and Biomark’s self-built library for identification; at the same time, theoretical fragment identification and mass deviation were within 100 ppm.