Trace gc ultra itq 900

GC–MS analyses were made in a laboratory of the Earth Science Institute, the Slovak Academy of Sciences in Banská Bystrica (Slovakia). Small amount of Sumatran resin (20–50 mg) was pulverized in an agate mortar and transported into 2 ml vials. Then, a mixture of the organic solvents dichloromethane and methanol (9:1) was added to the vial and left for three days at 50 °C. Thereafter, samples were sonicated and filtered on Pasteur pipets filled with silica wool and connected to a glass manifold with a vacuum. Extracts were analysed by GC–MS (TraceGC Ultra—ITQ900, Thermo Fisher Scientific), on 60 m nonpolar capillary column Zebron ZB5, connected to an ion-trap quadrupole with an electron-impact ionization for collection of mass spectra. Helium was used as a carrier gas. The temperature program was the following: 60 min at initial temperature of 70 °C, with one minute holding, than ramped to 180 °C at 30 °C min⁻¹ rate, and after that, ramped to 330 °C at 4 °C min⁻¹ rate. Finally, temperature was kept at 330 °C for 16 min. Analysed data were processed with the Xcalibur software with mass spectra library (NIST library), obtained mass spectra were additionally analysed by comparison to mass spectra reported in literature. The GC–MS results obtained for resin from Sumatra were discussed alongside GC–MS glessite data published by Yamamoto et al.^{32 (link)}.

The VOCs of different melons were detected under the procedure of headspace (HP)-solid phase micro extraction (SPME)-gas chromatography-mass spectrometry (GC-MS), as Liu and Tang was used (Liu et al., 2012 (link); Tang et al., 2015 (link)). About 100 g frozen melon flesh were thawed and squeezed into juice. 1-octanol (50 μl, 59.5 mg/l) were added into 10 ml juice samples as an internal standard. SPME needle was from Supelco (57347-U, Bellefonte, PA, USA), and GC-MS was from Thermo Scientific (Trace GC Ultra-ITQ 900, Waltham MA 02454). The GC system was equipped with a 30 m^*0.25 mm^*0.25 um thickness capillary column (Thermo TR-5 ms SQC, USA).
For incubation experiment, a 1 g aliquot of the melon powder was placed in a 10 ml glass vial containing 0.7 g of solid NaCl, 2 ml of a 20 % (w/v) NaCl solution (Gonda et al., 2010 (link)) and 10 μl of a 59.5 mg/l 1-octanol used as internal standard. Then, the sample was measured with the method mentioned above.

Headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC/MS) were carried out to extract the floral scent compounds in C. praecox. An empty capped vial was used as the negative control. The SPME device was equipped with an SPME fiber (50/30 μm) coated with polydimethylsiloxane (PDMS) (TriPlus 300, Thermo Fisher Scientific, Waltham, MA, USA). In detail, the protocols for HS-SPME followed the methods of Chen et al. [40 (link)]. Subsequently, a GC/MS system (Trace GC Ultra/ITQ900, Thermo Fisher Scientific, Waltham, MA, USA) with an HP-5MS capillary column (30 m × 0.25 mm × 0.25 μm, Agilent J & W Scientific, Santa Clara, CA, USA) was performed to identify the floral volatiles. The variation in the GC oven temperature and the data recorded from the mass spectrometer in electron impact mode (MS/EI) were based on the methods of Li et al. [37 (link)].