Gc 2010 plus gas

First, 100 µL of overnight bacterial culture (10⁶ CFU ml⁻¹) was transferred to 20 mL of sterile nutrient broth in a sterile GC-MS vial. The vials were sealed with parafilm to avoid the escape of volatile compounds and then placed in an incubator shaker for 48 h at 30 °C and 170 rpm. The vial was pierced with an SPME (Solid Phase Micro Extraction) device that absorbs VOCs from the headspace through fibers on the needle and secured with the router clamp for 40 min. Then, the SPME was placed on the GC-MS for 7 min and 34 s, and then removed. The GC-MS was carried out using a Shimadzu GC-2010 Plus gas chromatography system equipped with an Rtx-5MS 30 m × 0.25 mm ID; 0.25 μm GC capillary column coupled to a GCMS-QP2010 ULTRA MS [69 (link)]. The analysis of the compounds was completed within 30 min. The identification of the compounds was accomplished using the NIST 2011 v.2.3 and Wiley 9th edition mass spectrum libraries.

Two μL of nine essential oils were diluted to 1 mL by n-hexane. One μL of the essential oil solutions was analyzed by GC-MS using a Shimadzu GC-2010 Plus gas chromatography instrument coupled to a Shimadzu QP2010 Ultra mass spectrometer (Shim-Pol, Izabelin, Poland). Compounds were separated on a fused silica capillary column ZB-5MS (30 m, 0.25 mm i.d.) with a film thickness of 0.25 μm (Phenomenex, Torrance, CA, USA). The following oven temperature program was initiated at 50 °C, held for 3 min, then increased at the rate of 8 °C/min to 250 °C, held for 2 min. The spectrometers were operated in electron-impact (EI) mode, the scan range was 40–500 amu, the ionization energy was 70 eV, and the scan rate was 0.20 s per scan. Injector, interface and ion source were kept at 250, 250 and 220 °C, respectively. Split injection (1 μL) was conducted with a split ratio of 1:20 and helium was used as carrier gas of 1.0 mL/min flow-rate. The retention indices were determined in relation to a homologous series of n-alkanes (C8–C20) under the same operating conditions. Compounds were identified using a computer-supported spectral library (NIST 2011 - Gaithersburg, MD, USA; MassFinder 2.1 and 4.0—Hamburg, Germany), mass spectra of reference compounds, as well as MS data from the literature [48 ,49 ].