Pegasus 4d instrument

The GC×GC–TOF/MS analyses were performed using a LECO Pegasus 4D instrument (LECO Corp., St. Joseph, MI, USA) equipped with a non-moving quad-jet cryomodulator. DB-WAX (30 m × 250 μm × 0.25 μm) and DB-17HT (1.9 m × 100 μm × 0.10 μm) were used as the first and the second-dimensional columns, respectively. Helium (99.999%) was used as the carrier gas at a flow rate of 1 mL/min and the injection volume was 1 μL. The initial temperature of the first column was held for 5 min at 60 °C. After that, the temperature was increased to 240 °C at 3 °C/min and then held for 5 min. The initial temperature of the second column was held for 5 min at 65 °C. After that, the temperature was increased to 245 °C at 3 °C/min and then held for 5 min. The modulator was offset in relation to the secondary oven, the modulation cycle was 4.0 s, and the last was 0.7 s.
The mass spectrometry conditions were as follows. Electron ionizing source: ionizing energy, 70 eV; the mass scanning range was 41 to 415 u. The temperature of the conversion line was 250 °C, and the ion source temperature was 200 °C.
Data were processed and consecutively visualized on 2D and 3D chromatograms using LECO ChromaTOF™ software. The retention index (RI) was calculated using alkane standards (C₄–C₄₀; Sigma, Aldrich Trading Co., Ltd., Shanghai, China) at the same experimental conditions as mentioned above.

The initial screening for determination of differences and/or similarities in the cuticle profiles of Bactrocera spp. was performed with a Hewlett Packard HP 6890 GC System connected to a Hewlett Packard 5973 Mass Selective Detector. For analyses, an HP-5MS capillary column (30 m × 250 μm i.d. × 0.25 μm film; Agilent Technologies, Santa Clara, CA, USA) was used. Temperature was programmed from 150°C to 300°C at a rate of 5°C/min with 10 min final hold at 320°C. Samples (1 μl) were injected using a splitless mode with He as the carrier gas (constant pressure, 1 ml/min). Electron ionization at 70 eV was used in the range from 25 to 600 m/z, with ion source temperature 250°C and quadrupole temperature 150°C.
Detailed identification and quantification of the components was performed by GC×GC/MS, using a LECO Pegasus 4D instrument (LECO Corp., St. Joseph, MI, USA) equipped with a non-moving quad-jet cryomodulator connecting the 1st and the 2nd columns. The methodology has been described in detail elsewhere [23 ,25 (link),26 (link)]. A series of n-alkanes (C₁₂–C₄₀; Sigma-Aldrich) was used to determine the retention indices for the analytes. The compounds were identified by a comparison of their MS fragmentation patterns and retention indices with values published previously [22 (link),23 ,26 (link),29 ,32 ,33 (link)].