Chromatographic separation of analytes was performed using a 1290 Infinity II LC system (Agilent Technologies, Germany), consisting of a binary pump (G7120A), an autosampler (G7129B), and a column oven (G7116B). Samples were kept in the autosampler at room temperature (ca. 20 • C) and the injection volume was usually 1 µL. Analytes were separated on a Poroshell EC-C18 column (2.1 × 150 mm, 2.7 µm, Agilent Technologies, USA) at a constant flowrate of 0.5 mL/min and a column temperature of 40 • C. The mobile phases were water + 0.1% formic acid (A) and acetonitrile + 0.1% formic acid (B). The following gradient program was used for separation of analytes: at 0 min 95% A, at 1 min 95% A, at 21 min 5% A, at 23 min 5% A, at 23.1 min 95% A, and at 28 min 95% A. The HPLC system was connected to a G6546A quadrupole time-of-flight (Q-TOF) mass spectrometer (Agilent Technologies, USA), equipped with an electrospray ionization (ESI) source using the Dual Spray Agilent Jet Stream technology. The Q-TOF was operated in the highresolution mode for the low (m/z 1700) mass range. The acquisition rate was set to 6 Hz performing All Ion full scan measurements at alternating collision energies of 0, 20, and 40 eV, respectively. Data were always recorded for a mass range of m/z 50-1200 and the centroid, as well as profile storage mode was used. Ionization was performed in the positive mode and the ESI source was operated under the following conditions: drying gas temperature 225