2.3.3. UHPLC-HRMS Systems

Liquid chromatography analysis was performed using a Dionex UltiMate 3000 UHPLC system (Thermo Scientific, Oleten, Switzerland) equipped with a Kinetex PFP column (3.00 × 100 mm, 1.7 μm, 100 Å), obtained from Phenomenex (Torrance, CA, USA). LC system was coupled to a high-resolution mass spectrometer Q Exactive (Thermo Scientific, Bremen, Germany). LC parameters: 5 μL injection volume, 40 ◦C column temperature, 10 ◦C sample temperature, flow rate set to 0.450 mL·min−1, diverter valve was switched to mass spectrometer at 1.3 min. The mobile phase A (0.1% formic acid in H2O) and B (0.1% formic acid in MeCN) were used in gradient mode: 4 min preinjection equilibration held

at 2% B; 0–3 min at 2–5% B; 3–9 min at 5–98% B; 9–13 hold at 98% B; 13–14 return to the initial 2% B.

Heated electrospray (HESI) interface was used in positive and negative ionization mode, and polarity switching method was used with the following parameters: ion source voltage in negative/positive ionization (2500 V/3500 V), 280 ◦C temperature for ion transfer tube, 450 ◦C evaporator temperature.
