3800 gas chromatograph

Granules from the reactor were separated manually and transferred to reactor medium without a carbon source in a 20 ml glass bottle. The pH was set to 7.2. The bottles were then flushed with nitrogen gas to make them anaerobic. Methanol (20 mM) was injected and the bottles were incubated in a shaker set at 190 r.p.m. at 35°C. Samples were taken from the headspace at regular time intervals and the methane concentration in the headspace was determined on a Varian 3800 gas chromatograph. Gas samples were injected with a 100 μl gastight Hamilton syringe in a Varian Ultimetal 1079 split/splitless, which was operated at 200°C at a split ratio of 100. A CPSil5CB 5 (50 m × 0.32 mm) capillary column was used isothermally at 100°C at a constant gas flow rate of 10 ml min⁻¹. The used carrier gas was helium. Methane peaks were detected with a Varian flame ionisation detector that was operated at 300°C. The helium make-up flow was 25 ml min⁻¹, hydrogen flow was 30 ml min⁻¹ and air flow was 300 ml min⁻¹.

The volatile compounds were isolated by HS-SPME and analyzed by a Varian 3800 gas chromatograph (Darmstadt) equipped with a DB-FFAP capillary column (30 m × 0.25 mm i.d., 0.25 µm film thickness; J&W Scientific) coupled to an ion trap mass spectrometer Saturn 2000 (Varian) running in CI mode at 70 eV, with methanol as the reagent gas. Sample injections were performed by a CombiPAL autosampler (CTC Analytics, Zwingen, Switzerland) and a CAR/PDMS fiber (Supelco) was used for all experiments. The SPME conditions were applied according to a description of Senn et al. [35 (link)] with minor modifications. Therefore, sampling was performed for 30 min at 40 °C, and NaCl (1 g) was added to mead (5 mL) and weighed into gas-tight sample vials (20 mL). All analyses were performed in triplicates.

Minority volatile compounds were analyzed by GC-MS. The internal standard was 3.0 µL of buriti oil added in 10.0 mL dichloromethane and 100.0 µL of 4-nonanol (24.012 µg/mL), the mixture was kept refrigerated for further analysis. A Varian 3800 gas chromatograph (VARIAN, Palo Alto, CA, USA) with a 1079 injector and a Varian Saturn 2000 ion-lock mass spectrometer (VARIAN, Palo Alto, CA, USA) was used. Injections of 1.0 µL were performed in splitless mode (30 s) on a Sapiens-Wax MS column (30 m; 0.15 mm; 0.15 µm film thickness, Teknokroma, Barcelona, Spain). The carrier gas was helium 49 (PRAXAIR, Danbury, CT, USA)) at a constant flow rate of 1.3 mL/min. The detector has been set to electronic impact mode with ionization energy of 70 eV, a mass acquisition range of 35 to 260 m/z and an acquisition range of 610 ms. The oven temperature was initially set at 60 °C for 2 min and then increased from 60 to 234 °C at a rate of 3 °C/min, increased from 234 to 260 °C at 5 °C/min and finally kept at 260 °C for 10 min. Injector temperature was 250 °C with 30 mL/min split flow. The compounds were identified using MS Workstation software version 6.9 (Varian), comparing mass spectra and retention indices with those of pure standards. The minor compounds were quantified as 4-nonanol.

A Varian 3800 gas chromatograph was used to quantify the contaminants equipped with a Ni63 electron capture detector and a DB-5 (5% phenyl) methylpolysiloxane column measuring 30 m × 0.25 mm × 0.32 mm. The injector temperature was 270 °C and the detector was 300 °C. The initial temperature of the oven was 60 °C and it increased at a rate of 2 °C/min until reaching 300 °C, and this temperature was maintained for 5 min. The flow of nitrogen into the column was 2 mL/min and a makeup of 30 mL/min. Quantitative data were obtained by calculating the area under the curve with the Star Chromatography Workstation software (version 6) and using the calibration standards. Laboratory blanks were analyzed for quality assurance. Chicken egg samples were used in triplicate. One milliliter of a 200 ng/mL pesticide mix (SUPELCO) was added to the samples before the extraction, and they were subsequently refrigerated for 48 h. One of the subsamples was not spiked with the standard as a positive blank. Afterward, the contaminants were extracted and processed in a process identical to that used for the rest of the samples, with a recovery of >85%.

In order to characterize the flower scent chemistry of Campanula taxa, the headspace samples were analyzed on a Varian Saturn 2000 mass spectrometer coupled to a Varian 3800 gas chromatograph (GC/MS) equipped with a 1079 injector (Varian Inc., Palo Alto, CA, USA), which had been fitted with the ChromatoProbe kit [see 91] and a fused silica column ZB-5 (5% phenyl polysiloxane; 60 m long, inner diameter 0.25 mm, film thickness 0.25 µm, Phenomenex). Each quartz microvial was loaded into the probe, which was then inserted into the modified GC injector. Equipment configurations were identical to those published elsewhere [40 (link)].
Identification of compounds was carried out by using the NIST 08, Wiley 7 or Adams [92 ] mass spectral databases or the database provided in MassFinder 3 and were confirmed by a comparison of retention times with published data [92 ]. The structure assignments of individual components were confirmed by a comparison of mass spectra and GC retention times with those of available standards.
The composition of volatiles collected from flowering plants was compared with that from non-flowering plants (vegetative parts). Floral scent volatiles were those detected either at higher amounts (i.e., peak areas in chromatrogram of floral scent samples at least 10-fold larger than in leave samples) or exclusively in floral scent samples.