Amazon sl ion trap

The supernatant of fermentation broth was adjusted to pH ~3 by adding HCl, and then mixed with equal volume of ethyl acetate. Organic phase was dried using rotovap, and then dissolved in 1 ml of methanol. After being filtered by 0.2 μm filter, the crude extract was injected into HPLC. All HPLC analyses were carried out on Agilent 1260, equipped with a diode array detector, using analytical column Kinetex SB-C18 (4.6×180 mm, 5 μm) with a flow rate of 1.0 ml/min. Detector wavelengths were set to 220, 260, 280, 300, and 320 nm. Two methods were used for analytical HPLC. Solvent A was water with 0.1% trifluoroacetic acid (TFA), and Solvent B was acetonitrile with 0.1% TFA. Flow rate was set to 1.0 ml/min. Method 1: 5–30% B in 20 min, 30–100% in 10 min, hold at 100% for 4 min, 100–5% B in 1 min, hold at 5% B for 5 min. Method 2: 5–50% B in 15 min, 50–100% B in 5 min, hold at 100% B for 4 min, 100–5% B in 1 min, hold 5% B for 5 min. For LC-MS analysis, ESI positive ion mode (Bruker, Amazon SL Ion Trap) was used, equipped with a Kinetex 2.6 μm XB-C18 100 Å (Phenomenex).