An Agilent 1200 HPLC system (Agilent, USA) with electrospray ionization coupled to an Agilent 6460 triple quadruple mass spectrometer (LC-ESI-MS/MS) was used to confirm the structures of the GSLs. The HPLC conditions were the same as those mentioned in the previous section, and the mass conditions are listed in Table 6 . Compounds with m/z = 75 and featuring [M-G-H]− molecular ion peaks were selected as candidate compounds [90 (link), 91 ]. The positive ion peak, such as [M-G + H]+, was used for identification [51 (link), 92 (link)]. For MS/MS conditions, the fragmentor voltage was optimized by approximately 1/3 of the molecular weight, and the collision energy number was set to approximately 1/15 of the given molecular weight.
LC-MS/MS conditions
| Items | Parameters |
|---|---|
| Gas Temp | 300 °C |
| Gas Flow | 10 L/min |
| Nebulizer | 45 psi |
| Sheath Gas Temp | 350 °C |
| Sheath Gas Flow | 11 L/min |
| Capillary | 3000 V(+)/3000 V(−) |
| Nozzle Voltage | 500 V(+)/500 V(−) |
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