Vf 624 ms column

The cell-free culture filtrate of each antagonistic fungus was extracted three times for 30 min each time with equal volumes of ethyl acetate and n-butyl alcohol. After combining the extract liquor, the ethyl acetate phase and the n-butyl alcohol phase were obtained separately. The extract liquor of each phase was concentrated to 5 mL under reduced pressure at 35–45°C. All samples were filtered through a 0.22 µm nylon membrane prior to GC‒MS.
The analysis of volatile components in culture filtrates was carried out on a GC‒MS (FULI-Chromatec Crystal 9000). An Agilent VF-624 ms column (60 m × 0.25 mm × 1.4 μm) was used with hydrogen as the carrier gas, and the flow rate was 1 mL/min. A 1 µL sample was injected in splitless mode, and the vaporizer temperature was 220°C. The oven was programmed to start at 35°C (held for 4 min) and to ramp up to 95°C at 6°C/min (held for 3 min), and then, it was increased to 230°C at 15°C/min (held for 15 min). The ion source temperature was set at 230°C. The ionizing electron energy was 70 eV, and the scan range was 35–350 u. Compounds were identified using the National Institute of Standards and Technology database version 17.0. The results were expressed as a percentage of the volatile organic compounds by dividing the area of each peak by the total area of the chromatogram peaks.^{35 (link)}

Six different coatings of the sorbent tubes were tested with the development solution. Carbosieve SIII, Carbotrap 202, and Carbopack B were obtained from Sigma-Aldrich (Bornem, Belgium); Tenax TA, Tenax/Unicarb, and Tenax/Carboxen 1003/Carbopack B were purchased from Camsco (Houston, TX).
As GC columns, a VF-5ms column (30 m × 0.25 mm × 0.25 μm) was tested first. Next, a VF-35ms column (30 m × 0.25 mm × 0.25 μm) and a VF-624ms column (60 m × 0.25 mm × 1.4 μm) from Agilent Technologies (Diegem, Belgium) were obtained and evaluated. The applied temperature gradient was also optimized.