Ltq xl

Quantitative assessment of phenolic compounds was carried out through HPLC–MS (LTQ XL, Thermo Fisher Scientific, San Jose, CA, USA) analysis (Świeca et al. 2012 (link)). The HPLC–MS system was equipped with a ternary pump, auto sampler, and thermostatic column compartment, diode array detector (Surveyor, Thermo Fisher), and a linear ion trap mass spectrometer (LTQ XL, Thermo Fisher Scientific, San Jose, CA, USA) equipped with an electrospray ionization (ESI) source. A CORTECS C18 column (2.1 mm × 100 mm, 2.6 µm; Waters) was used; the column temperature was maintained at 35 °C. The mobile phase A (0.1% formic acid/water) and B (acetonitrile) was used, the gradient program was as follows: 0–2 min 5.0% B; 4–11 min 15–35% B; 15–17 min, 100% B; 17.5–22 min, 5.0% B; flow rate was 0.25 mL min⁻¹, the injection volume was 4 μL. UV detection was performed at 270 and 370 nm, the wavelength was scanned from 200–600 nm. MS was scanned in ESI source in negative mode, mass range: m/z 92–1000; source voltage was 3.5 kV, capillary temperature was 350 °C, sheath gas flow was 35, aux gas flow was 15.0, sweep gas flow was 1.0, and capillary voltage was 43 V. Data acquisition, handling, and instrument control were performed using Xcalibur 2.3.1 software.

MS detection was carried out using an LTQ-XL ion trap mass spectrometer (LTQ-XL, Thermo Scientific, San Jose, CA, USA). The temperature of the ion transfer capillary was 150 °C. The capillary voltage was 1.0 V. The tube lens voltage was 30.0 V. The pressure of ion trap was 1 × 10^–5 torr. High-purity helium (99.999%) was used as the collision gas. The CID-MS experiments were performed by applying excitation alternating current voltage to the end caps of the ion trap to induce collisions of the isolated ions. The CID-MS spectra were obtained by activation of the precursor ions at the normalized collision energy varied from 0% to 50%. Ion detection was done in the positive ion mode. Other LTQ-XL parameters were automatically optimized by the system.