Db wax gc column

Samples for volatile compounds (VOCs) analysis were isolated from the packed fillets of the consumer study. The VOCs were determined by headspace SPME-GC/MS analysis according to Katsouli et al. [18 (link)] based on a modified procedure of Parlapani et al. [20 (link)]. Specifically, volatiles were extracted by homogenizing 5 g of minced fish muscle with 4 mL of saturated saline and incubated at 40 °C for 15 min. The SPME fiber (50/30UM DVB/CARBOXEN-PD) was exposed to the headspace for an additional 40 min, under the same conditions. The headspace was then analyzed using gas chromatography–mass spectrometry (Agilent Technologies, Santa Clara, CA, USA) and the separation was achieved on an Agilent DB-WAX GC Column (30 m 0.25 mm, coated with a 0.25 μm film thickness). 4-methyl-1-pentanol was used as an internal standard; and the identification of the compounds was based on comparing MS data with those of reference compounds and by MS data obtained from the NIST library (NIST/EPA/NIH Mass Spectral Library with Search Program, software version 2.0f) and by semi-quantitative analysis using the method of internal standard. All samples were analyzed in triplicate.

The experiment was conducted at the Instrument Analysis Center, Shanghai Jiao Tong University. A DB-Wax GC column (length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm; Agilent 7890 B) coupled with a mass spectrometer (Pegasus BT, MI, United States) was used for the separation of volatile components. The column temperature was held initially at 60 °C for 5 min, increased to 180 °C at the rate of 3 °C/min, then raised to 250 °C at the rate of 10 °C/min and held for 5 min [12 (link)]. Helium was used as the carrier gas with a 1 mL/min flow rate. The mass spectrometer conditions were set as follows: ion source and interface temperatures were 300 °C and 275 °C, respectively. The ionization potential of MS was 70 eV, and the scan range was 50 to 350 m/z for 2 s [24 (link)].
The retention times of n-alkanes (C₄–C₃₀; Sigma, Aldrich Trading Co., Ltd., Shanghai, China) were obtained at the same experimental conditions as mentioned above in order to calculate the retention index (RI) of the volatile organic compounds (VOCs).