Kinetex ps c18

Ceftobiprole was obtained from Basilea Pharmaceutica International Ltd. (Basel, Switzerland), manufactured on March 2017 and stored in a freezer at −20 °C). Deionised water was obtained from a Labconco System by Millipore (Bedford, MA, USA). Acetonitrile (ACN, gradient grade for HPLC, ≥99.9%), ACN for LC-MS (≥99.9%), methanol (MeOH, gradient grade for HPLC, ≥99.9%) and DMSO (for HPLC, 99.7%) were obtained from Honeywell (Charlotte, NC, USA). Sodium hydroxide (≥98.8%), ammonium hydrogencarbonate (≥99.0%) and ammonium formate (≥99.0%) were delivered by Chempur (Piekary Śląskie, Poland); HCl (pure p.a., 35–38%) and H₂O₂ (pure p.a., 30%) were bought from POCH (Gliwice, Poland); acetic acid (for LC-MS, 99.8%) and ammonium acetate (reag. Ph. Eur., ≥98.0%) were purchased from Merck (Darmstadt, Germany); acetic acid (pharma grade, 99.9%) was obtained from AppliChem (Darmstadt, Germany); and ammonium acetate (for LC-MS, ≥99.0%) and formic acid (reag. Ph. Eur., ≥98%) were manufactured by Sigma-Aldrich (Darmstadt, Germany).
The following chromatographic columns were used: Kinetex C18 (150 × 3 mm, 2.6 μm), Kinetex PS C18 (150 × 2.1 mm, 2.6 μm) and Kinetex Biphenyl (150 × 2.1 mm; 1.7 μm) from Phenomenex (Torrance, CA, USA), as well as Accucore AQ C18 (150 × 4.6 mm, 2.6 μm) from Thermo Fisher Scientific (Waltham, MA, USA).

Mass spectrometry data were acquired by using a LTQ Orbitrap XL interfaced to an Ultimate 3000 RS (Thermo Fisher Scientific). Polyphenol separation was achieved through a thermostated (35°C) core-shell reversed phase column with a positive charge surface (Kinetex PS C18, 100 x 2.1 mm, 2.6 µm, Phenomenex). Mobile phases consisted in 0.1% formic acid in water (solvent A) and 0.1% formic acid in methanol (solvent B). Samples (5 µL) were injected in full loop mode and analytes were resolved through the following gradient of solvent B (minutes/%B): (0/10), (2/10), (12.5/55), (14/55), (17/95), (19/95), at a flow rate of 0.2 mL/min, with an equilibration stage of 6.5 min at 10% of mobile phase B. Analytes were screened in negative ion top four untargeted data dependent scanning mode; ESI interface spray voltage and capillary voltage were -4.2 kV and -70.0 V, respectively. Capillary temperature was 275°C; sheath gas and auxiliary gas flow values were 25 and 3 arbitrary units, respectively. Profile data type were acquired in full scan Fourier transformed mass spectrometry (FTMS) mode in the mass scanning m/z range 70–1200. For data dependent scanning, MS/MS normalized collision energy was 25, activation Q was 0.25, activation time was 25 ms, with a 1 m/z isolation window, while a reject mass list was generated by injecting blank samples.