Vanquish flex ultra performance liquid chromatography

For metabolomics analysis by LC-MS, separation was carried out using the Vanquish Flex Ultra-performance liquid chromatography (UPLC) along with the Q Exactive MS (ThermoFisher, Waltham, MA), and it was screened with electrospray ionization MS (ESI-MS). The LC system comprised the ACQUITY UPLC HSS T3 (100×2.1 mm×1.8 μm) with UPLC. The mobile phase was composed of 0.05% formic acid water and acetonitrile with gradient elution (0-1 min, 5% acetonitrile; 1-12 min, 5%-95% acetonitrile; 12-13.5 min, 95% acetonitrile; 13.5-13.6 min, 95%-5% acetonitrile; 13.6-16 min, 5% acetonitrile). The flow rate of the mobile phase was 0.3 mL/min. The column temperature was maintained at 40°C, and the sample manager temperature was set at 4°C. MS in ESI+ and ESI− mode were listed as follows: (1) ESI+: Heater Temp 300°C; Sheath Gas Flow rate, 45 arb; Aux Gas Flow Rate, 15 arb; Sweep Gas Flow Rate, 1 arb; spray voltage, 3.0 KV; Capillary Temp, 350°C; S-Lens RF Level, 30%; and (2) ESI−: Heater Temp 300°C, Sheath Gas Flow rate, 45 arb; Aux Gas Flow Rate, 15 arb; Sweep Gas Flow Rate, 1 arb; spray voltage, 3.2 KV; Capillary Temp,350°C; S-Lens RF Level, 60%.