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.