LCMS Analysis of Compounds in Positive and Negative Modes

The positive ion mode is adjusted as follows: Agilent Poroshell 120 SB-C18 (100 mm × 4.6 mm, 2.7 μm) is used; the mobile phase consists of 0.1% formic acid water (A)–acetonitrile (B); gradient elution conditions are 0–25 min, 5–40% B; 25–35 min, 40–75% B; 35–40 min, and 75–100% B; the flow rate is 0.8 ml min⁻¹; the column temperature is 30°C; the injection volume is 1 μl; the electrospray ion source (ESI) is detected in the positive ion mode; the drying gas flow is 13 L/min; the drying gas temperature is 350°C; the capillary voltage (Vcap) is 4,000 V; the neutralizer pressure is 45 psig; the fragmentor voltage is 125 V; the skimmer voltage is 65 V; the mass scanning range is 50–1,000 m/z; and the secondary MS collision voltage is 40 eV.
The negative ion mode is set as follows: Agilent Poroshell 120 SB-C18 (100 mm × 4.6 mm, 2.7 μm) is used; the mobile phase consists of water (A)–acetonitrile (B); gradient elution conditions are 0–30 min, 5–100% B; the flow rate is 0.8 ml min⁻¹; the column temperature is 30°C; the injection volume is 5 μl; the drying gas flow is 11 L/min; the drying gas temperature is 250°C; the Vcap is 3,500 V; the neutralizer pressure is 45 psig; the fragmentor voltage is 125 V; the skimmer voltage is 65 V; the mass scanning range is 50–1,000 m/z; and the secondary MS collision voltage is 40 eV (Wang et al., 2021 (link)).