. HPLC–ESI-FT (Orbitrap) MS analysis
A Thermo Scientific Accela 600 pump HPLC system was used in
the experiment, equipped with a binary pump and an autosampler.
A Waters Atlantis T3 (2.1 150 mm, particle size 5 lm) column
was used for separation of the steviol glycosides at room temperature.
Water containing 0.05% formic acid (solvent A) and
574 S. Soufi et al. / Food Chemistry 190 (2016) 572–580
acetonitrile (solvent B) were used as mobile phases. The flow rate
was 0.2 mL/min and elution conditions at room temperature
applied with a linear gradient as follows: 0–5 min, 10% B; 5–
25 min, 80% B; 27–30 min, 100% B; 31–36 min, 10% B. Mass spectrometric
detection was performed using an LTQ-Orbitrap hybrid
mass spectrometer (Thermo Fisher Scientific, Bremen, Germany)
fitted with an electrospray source (ESI) operating in positive ionisation
mode. Nitrogen was used as the sheath and auxiliary gas
and helium as the collision gas. Values of auxiliary gas flow rate
and capillary voltage were set respectively at 5 arbitrary units
and 1. The ESI source was operated with capillary voltage at
49 V, tube lens voltage 250 V and capillary temperature at
280 C. In the FT experiment, resolution of the Orbitrap mass analyser
was set at 30,000 (Full width at half maximum (FWHM) as
defined at m/z 400). The collision energy for CID was adjusted to
35% of maximum, and the isolation width of precursor ions was
m/z 2.0 Da. The mass spectrometric spectra were acquired by full
. HPLC–ESI-FT (Orbitrap) MS analysisA Thermo Scientific Accela 600 pump HPLC system was used inthe experiment, equipped with a binary pump and an autosampler.A Waters Atlantis T3 (2.1 150 mm, particle size 5 lm) columnwas used for separation of the steviol glycosides at room temperature.Water containing 0.05% formic acid (solvent A) and574 S. Soufi et al. / Food Chemistry 190 (2016) 572–580acetonitrile (solvent B) were used as mobile phases. The flow ratewas 0.2 mL/min and elution conditions at room temperatureapplied with a linear gradient as follows: 0–5 min, 10% B; 5–25 min, 80% B; 27–30 min, 100% B; 31–36 min, 10% B. Mass spectrometricdetection was performed using an LTQ-Orbitrap hybridmass spectrometer (Thermo Fisher Scientific, Bremen, Germany)fitted with an electrospray source (ESI) operating in positive ionisationmode. Nitrogen was used as the sheath and auxiliary gasand helium as the collision gas. Values of auxiliary gas flow rateand capillary voltage were set respectively at 5 arbitrary unitsand 1. The ESI source was operated with capillary voltage at49 V, tube lens voltage 250 V and capillary temperature at280 C. In the FT experiment, resolution of the Orbitrap mass analyserwas set at 30,000 (Full width at half maximum (FWHM) asdefined at m/z 400). The collision energy for CID was adjusted to35% of maximum, and the isolation width of precursor ions wasm/z 2.0 Da. The mass spectrometric spectra were acquired by full
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