A Thermo Accela 1250 HPLC equipped with an auto-sampler and a UV-visible detector (Thermo Fisher Scientific, San Jose, CA, USA) was employed for the analysis of crude alkaloids. A 10 μL sample was analyzed on a Phenomenex Kinetex column (2.6 μm, C18, 100 × 2.1 mm) at 25 °C. The flow rate was 0.2 mL/min and the chromatograms were recorded at the wavelength of 280 nm. 0.5% formic acid solution (adjusted to pH = 4.5 by ammonium, A) and acetonitrile (B) were selected as mobile phase, and the gradient was set as follows: 0–25 min, 5–20% (B); 25–40 min, 20% (B); 40–55 min, 20–35% (B); 55–65 min, 35–80% (B).
For ESI-MS/MS analysis, a Thermo Accela 600 HPLC system with both UV detector and TSQ Quantum Access MAX mass spectrometer (Thermo Fisher Scientific, San Jose, CA, USA) was used for the LC-MS analysis in the positive mode. The mass condition was set as follows: mass range from 200 to 800 Da; Spray Voltage, 3.0 kV; Capillary temperature, 350 °C; Sheath gas pressure, 40 psi; Aux gar pressure, 10 psi.
For ESI-MS/MS analysis, a Thermo Accela 600 HPLC system with both UV detector and TSQ Quantum Access MAX mass spectrometer (Thermo Fisher Scientific, San Jose, CA, USA) was used for the LC-MS analysis in the positive mode. The mass condition was set as follows: mass range from 200 to 800 Da; Spray Voltage, 3.0 kV; Capillary temperature, 350 °C; Sheath gas pressure, 40 psi; Aux gar pressure, 10 psi.