LC-MS/MS Analysis of Compounds

LC–MS/MS analysis was performed using an Accela UHPLC system (Thermo Fisher Scientific, CA, USA) coupled with a high-resolution LTQ-Orbitrap XL hybrid mass spectrometer (Thermo Electron, Bremen, Germany) via an ESI interface. Sample separation was performed at 40 °C using a Waters BEH C18 column (2.1 × 150 mm, 1.7 μm). Water (A) and acetonitrile (B) were used as the mobile phase, with 0.1% formic acid being added to both solvents. The flow rate was adjusted to 400 μL/min. The elution gradient was as follows: 0% B (0–1 min), 0–40% B (1–20 min), 40–100% B (20–24 min), and 100% B (24–27 min). The sample (2 μL) was injected, and the analysis was performed using PDA at 200–600 nm and MS at m/z 100–1000 in the positive ion mode. The conditions of the ESI source were similar to those of a previous study. The compounds were identified using the reference literature [25 (link)], high-resolution mass spectra, and MS/MS spectral library search [26 (link)].