Esi q tof ms

Reaction products were identified by LC-MS (Chromatograph Series 1260) coupled to ESI-Q-TOF-MS (6520, Agilent Technologies, Santa Clara, California, USA). The separation was performed on a ZORBAX SB C18-Selec column (4.1 × 100 mm, 5 μm). The parameters of the ESI source were the following: Negative ionization mode, fragmenter voltage: 175 V, capillary voltage: 3500 V, gas temperature: 350 °C, N₂ flow: 11 L min⁻¹, nebulizer pressure: 60 psi, and the flow rate: 0.7 mL min⁻¹.

APGD-MS experiments were performed with a homemade ion source of APGD (Figure 6) coupled with a triple quadrupole mass spectrometer (Agilent Technologies, Santa Clara, CA, USA). The APGD ion source consisted of a quartz tube, titanium tube anode, and tungsten cathode. The APGD-MS experiments were carried out with the gas flow rate in the range of 100–600 mL/min, discharge voltage in the range of 765–1005 V, interelectrode gap distance in the range of 2–8 mm, and distance between the anode orifice and the MS inlet ranging from 3–15 mm. The basic parameters of MS were performed with m/z in the range of 10–500 and collision energy range in the range of 1–20 eV. The collision gas was nitrogen. The catalytic ability of PPO measured the absorbance at 475 nm by a UV–Vis spectrophotometer (SPECORD 50 PLUS, Analytik Jena, GA, Jena, Germany). The ESI-Q-TOF-MS (Agilent Technologies, Santa Clara, CA, USA) was determined to perform the experiments.

The characterization of the polyphenols in the fraction with the highest activity was performed by HPLC-ESI-QTOF-MS. Solid-phase extraction of polyphenols was carried out using Oasis HLB 1 cc Vac Cartridges (Waters, Milford, MA, USA).
The separation of polyphenols was conducted as previously described by Sánchez-Faure et al. [15 (link)] using an HPLC Agilent 1200 (Agilent Technologies, Waldbronn, Germany) equipped with a diode array detector (DAD, ref. G1315B) and an ESI-QTOF-MS (Agilent G6530A). The mass spectrum was obtained by electrospray ionization in negative and positive modes. The gas temperature was 325 °C, and the drying gas flow was 12 L/min. Scans were acquired for auto MS/MS from 100 to 1200 m/z. The MassHunter Workstation software version 4.0 (Agilent Technologies) was used to analyze the mass spectra. The phenolic compounds were identified with the molecular formula proposed by the software and comparing the experimental mass with the exact mass, allowing an error of 8 ppm. The fragmentation pattern and relative abundance of fragmentation ions were compared with the fragmentation patterns found in the public databases, Human Metabolome Database and MassBank. The relative abundance of each tentatively identified compound was determined by measuring its peak area.