Agilent 7890a 5975c gc ms

The commercial standards of 28 VOCs were purchased from several manufacturers. Detailed information regarding the manufacturers, purities and uncertainties of the purities are given in Table 6. Pesticide residue grade methanol was purchased from J.T. Baker, USA. The stock standard solutions were 27 mixed VOCs standard solution (IRMM, 100 µg/mL) and vinyl chloride standard solution (2000 µg/mL, Supelo, USA). The internal stock standard solutions were fluorobenzene and 1,4-dichlorobenzene D₄ (IRMM, 1000 and 1000 µg/mL, respectively).
The VOCs spiking solution was prepared gravimetrically using a calibrated Mettler Toledo analytical balance (AE-240, 205 g capacity, resolution of 0.01 mg, Switzerland). The purities of the 28 VOC commercial standards were verified by a calibrated gas chromatography with flame ionization detection (Agilent 7890A GC-FID, USA). Homogeneity and stability studies of VOCs spiking solution were performed on a calibrated Agilent 7890A gas chromatograph coupled with an Agilent 5975C mass spectrometer (Agilent 7890A GC-5975C MS, USA). Analysis of the water MCRM was performed on a calibrated purge-and-trap Agilent 7890A GC-5975C MS.

An Agilent 5975C‐7890A GC‐MS (Agilent Technologies) was equipped with an olfactory detection port Gerstel ODP‐2 (Gerstel AG Enterprise). The GC was fitted with HP‐INNOWAX column (60 m × 0.25 mm × 0.25 µm; Agilent). The oven temperature was programmed from 40°C and the initial temperature was 1 min and increased to 230ºC at 5ºC/min and then kept for 3 min, and the high‐purity nitrogen was used as the carrier gas at 1.8 ml/min. The temperature of the injector port was 250°C, and 0.5 µl of each sample was injected into the GC‐MS‐O system. Each GC‐O experiment was evaluated by three panelists (two females and one male). All the panelists were trained for 30 hr over a period of 3 weeks. The aroma character of volatile compounds was evaluated by sniffing, and intensity of the volatile compounds was marked with five scales (“1” mean extremely weak, “3” impress medium odor, “5” mean extremely strong; Sheibani et al., 2016a). These volatile compounds were identified by matching their RI values with standards.
The aroma intensity was based on the aroma character of GC‐O as well as the sensory evaluation.

An Agilent 5975C-7890A GC-MS (Agilent Technologies, Palo Alto, CA, USA) was equipped with an olfactory detection port Gerstel ODP-2 (Gerstel AG Enterprise, Mülheim an der Ruhr, Germany). The GC was fitted with HP-INNOWAX column (60 m × 0.25 mm × 0.25 μm, Agilent, Palo Alto, CA, USA). 0.5 µL of the sample was injected into the GC-MS-O system in a splitless mode. The oven temperature was started at 40 °C for 1 min, and increased in a rate of 5 °C/min to 230 °C and then kept for 3 min. High purity nitrogen was used as the carrier gas at 1.8 mL/min. Temperature of the injector port was 250 °C.
GC-MS-O experiment was performed by three panelists (two females and one male). All the panelists were trained for 30 h over a period of 3 weeks using a series of standards solutions, so as to recognize, describe and discriminate the odors of different compounds. Each volatile was recorded with the retention time (RT), sniffed aroma attribute and the aroma intensity (AI). The AI was ranked in five levels, where “1” means extremely weak, “3” impresses medium, “5” means extremely strong [40 (link)]. The odorants were detected by at least two panelists were recorded. The experiment was replicated in triplicate by each panelist, and the AI was averaged.