ABSTRACT: In this study, an enhanced structure-guided molecular networking (E-SGMN) method was used, which is specifically tailored for the Orbitrap Astral mass spectrometer.
Reverse phase liquid chromatography (RPLC) analysis. ACQUITY BEH C8 column (100 mm×2.1 mm, 1.7 ?m, Waters, Milford, MA, USA) was used for the LC system in positive (ESI+) ionization modes, respectively. The temperature was set to 50°C, and the gradient elution flow rate was set at 0.35 mL/min. The mobile phase consisted of water (A) and acetonitrile with 0.1% formic acid (B) in ESI+ ionization mode. The initial gradient started with 5% B for 1 min, followed by a linear increase to 100% B within 23 min, and then maintained for an additional 4 min. Finally, the gradient was reduced to 5% B for system equilibration.
Astral MS analysis. Mass spectrometry was performed on Orbitrap Astral (Thermo Fisher Scientific, Rockford, IL, USA) in full scan MS/ddMS2 mode. For the full scan properties of the Orbitrap detector, the MS1 scan range was 85-1250 m/z. Orbitrap resolution was 120,000. RF lens was set as 50%. Full-scan orbitrap MS1 was performed in parallel with fast and sensitive DDA MS2 (top 30) on the Astral mass analyzer, with an MS/MS acquisition rate of 150 Hz. The isolation window was 1 m/z. Normalized collision energy type was used in our work, and the HCD collision energy was set as 15%, 30%, 45% and 80%, respectively. The MS2 scan range was 50-1250 m/z. The normalized AGC target and injection time were 10% and 5 ms, respectively. The spray voltages were 3.5 kV and 3.0 kV in positive and negative ionization modes, respectively. The aux gas heater temperature and capillary temperature were 350°C and 320°C, respectively. The sheath gas and aux gas were 45 and 10 (in arbitrary units), respectively.