Bactrocera Cuticle Profiling by GC-MS

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)].