Pegasus 4d mass spectrometer

Solid-phase microextraction (SPME) used for the determination of VOC was carried out with the method of Carlin et al. [57 (link)], as we described previously [8 (link)]. All samples were analyzed by GCxGC TOF-MS. Analysis was performed using a Pegasus 4D mass spectrometer equipped with a consumable-free dual-stage, quad-jet thermal modulator (LECO Corp.). A BPX5 (30 m, 0.25 mm, 0.25 μm) was used as a first-dimension (1D) column, and a BPX50 (2 m, 0.1 mm, 0.1 μm) was used as a second-dimension (2D) column. The mass spectra of detected compounds were identified with the aid of the National Institute of Standards and Technology Mass Spectral Library (version 2.0g). Each VOC content was presented as a relative peak area.

The analyses of oil and volatile compounds were performed on an Agilent (Santa Clara, CA, USA) 6890 N gas chromatograph (GC) with an automatic liquid sampler Agilent 7683B coupled to a LECO Pegasus 4D mass spectrometer. The separation was achieved on a DB-5 capillary column (30 m × 0.25 mm i.d., 0.25 μm film thickness). Gas chromatograph oven initial temperature was kept at 40 °C for 3 min, then increased to 300 °C at 20 °C/min and held for 5 min. The injector temperature was maintained at 300 °C, using splitless injection mode (2 min). Helium was used as carrier gas with a constant flow-rate of 1 mL/min. The mass spectrometer was operated in scan mode from 45–500 m/z; ion source temperature was set at 200 °C; the ionization was performed in the impact ionization mode (EI) with the ionization voltage set to 70 eV.