2.2.2. Equipment and analytical conditions
Ultra Performance Liquid Chromatography was employed using an ACQUITY UPLC™ System (Waters, Milford, MA, USA) coupled to a triple quadrupole mass spectrometer (Micromass TQ Detector from Waters, Manchester, UK) through an orthogonal-Z-spray ionization source. The separations were performed using an ACQUITY UPLC® BEH C18 RP Shield (1.7 mm2.1 100 mm) column from Waters at a flow rate of 0.3 mL min1 and 40 C temperature. Mobile phase consisted of A (0.5 mM NH4Ac þ 0.1% formic acid in water) and B (MeOH 100%) programmed with a time gradient that started at 20% B during 1 min, then linearly increased to 100% B in 1.6 min, remained in pure MeOH for 2.4 min, and finally returned to
initial conditions in 1 min