Db 624 ui capillary column

The VOC concentrations of the samples were analyzed using gas chromatography-mass spectrometry (GC-MS) in the electron ionization mode. Chromatographic separation was performed on an Agilent 7890A GC system (Agilent Technologies, Santa Clara, CA, USA) equipped with an Agilent 5975C with a triple-axis detector (Agilent Technologies, USA). A split injection of 1 μL with a split ratio of 50:1 was made with the 7693A automatic sampler (Agilent Technologies, USA). A DB-624 UI capillary column (60 m × 250 μm × 1.4 μm, Agilent Technologies, USA) was used. Ultrahigh purity helium was used as the carrier gas, flowing at 1 mL/min. The oven was programmed at 40 °C for 5 min, 7 °C/min to 230 °C, and 230 °C for 5 min. The data were quantified using selective ion monitoring.
The extracted VOCs from the resin were analyzed using GC-MS, whereas Headspace-GC-MS (HS-GC-MS) was used to detect VOCs in the water samples. HS-GC-MS measurements were carried out with an HS autosampler (TriPlus 300, Thermo Scientific, Waltham, MA, USA). Table 2 shows the HS autosampler operating conditions. A 20 mL headspace screw vial (Thermo Scientific, USA) was used.

For the analysis of higher alcohols, 50 mL of fermentation samples and 50 mL of deionized water were distilled to collect 50 mL of distillates. A total of 9.9 mL of distilled solutions were mixed with 100 μL of 2% (v/v) amyl acetate (internal standard), and filtered through a 0.22 µm filter for gas chromatography (GC) analysis [6 (link)].
Higher alcohol contents were determined using an Agilent 7860 GC equipped with a DB-624UI capillary column (60 m × 0.32 mm × 1.8 μm) and an FID detector (Agilent Technologies, Santa Clara, CA, USA) based on our lab optimization. The chromatographic conditions were based on the National Standard Method of Analysis for Baijiu (GB/T 10345-2022) [19 ] with some modifications. The detector and the injection temperature were 220 °C, and the injection volume was 1 μL. The carrier gas was hydrogen at 2 mL/min, and the split ratio was 37:1. The oven temperature was initially held at 30 °C for 6 min, increased to 40 °C at a heating rate of 2 °C/min and held for 2 min, then increased to 100 °C at a rate of 5 °C/min and held for 10 min, and finally raised to 200 °C at the rate of 10 °C/min and held for 10 min. The standard samples of n-propanol, isobutanol, isoamyl alcohol, 2-methyl-1-butanol and β-phenylethanol were used for qualitative and quantitative analysis of higher alcohols.