Agilent 7890a gc ms instrument

Samples were extracted with 100% methanol and centrifuged for 5 min at 4,500 rpm (Centrifuge MiniSpin plus, Germany). The supernatants were characterized by GC–MS without derivatization using an Agilent 7890A GC–MS instrument (Agilent Technologies, United States) equipped with an Agilent HP-5MS UI capillary column (0.25 μm, 0.25 mm × 30 m). The carrier gas was helium, and the flow rate was 2 mL/min. The injector temperature was 260°C, and the G4513A auto-injector was used with 1 µL injections in splitless mode. The oven was preheated to 50°C; the temperature was then elevated to 310°C at a rate of 10°C per minute, for a total of 25 min. The MS intake temperature was set to 260°C, the MS ion source temperature was 230°C, and the interface temperature was 280°C.

The detailed reaction conditions are described in the figure captions and table footnotes. In a typical reaction, catalyst (0.2 g) and lignin (0.1 g) were loaded into a stainless-steel autoclave reactor (Anhui Kemi Machinery Technology Co., Ltd) with water (15 ml) as the solvent. After the reactor was purged with H₂ three times and charged with 0.7 MPa H₂, the reaction was conducted at 250 °C with a magnetic stirring speed of 600 r.p.m. After the reaction, the reactor was quenched to ambient temperature in an ice-water bath, and the organic products were extracted using ethyl acetate and analysed by gas chromatography (GC) and GC–MS on an Agilent 7890B gas chromatograph with flame ionization detector and an Agilent 7890A GC-MS instrument, both equipped with HP-5 capillary columns (30 m × 250 μm). Tridecane was used as an internal standard for the quantification of the liquid products. For the stability test, after each reaction, the used catalyst was isolated, briefly washed with ethanol to remove the unreacted lignin feedstock and dried at 80 °C in air before the next run.