Turbo matrix 650 automatic thermal desorber

Volatiles collected in the absorption pipes were enriched using a Turbo Matrix 650 Automatic Thermal Desorber (PerkinElmer, Waltham, MA) with a two-stage heating program. The carrier was high-purity helium. The volatiles in the adsorption pipes were desorbed at 260℃ for 10 min, and then reabsorbed in the cold trap (− 30℃), which was heated to 300℃ at a rate of 40℃/s for 5 min, and finally moved into the GC through a capillary transfer line (250℃). The conditions of the Clarus 600 Gas Chromatograph (PerkinElmer) were as follows: DB-5MS UI chromatographic column (30 m • 0.25 mm • 0.25 μm; Agilent Technologies, Santa Clara, CA); initial temperature of 40℃ for 2 min, increased to 180℃ at 6℃/min, followed by an increase to 270℃ at 15℃/min for 3 min. The conditions of the Clarus 600 T Mass Spectrometer (PerkinElmer) were as follows: electron ionization at 70 eV; mass scan range of 30 to 500 m/z; and interface and ion source temperatures of 250℃ and 230℃, respectively.
The volatiles were analyzed by TurboMass 5.4.2 GC–MS software (PerkinElmer, Shelton, CT). The volatiles were identified by matching their retention times, characteristic ions, and mass spectra with the NIST 08 library (National Institute of Standards and Technology, Gaithersburg, MD). The relative contents of individual volatiles were calculated by the area normalization method.

The automatic thermal desorption gas chromatography–mass spectrometry analysis was derived from Zhou et al.^{18 (link)}. In brief, the adsorption pipe was heated (260 °C for 10 min) to desorb volatiles, then they were enriched with cold-trapping (− 30 °C for 3 min) and were heated again (300 °C for 5 min) by a Turbo Matrix 650 Automatic Thermal Desorber (PerkinElmer, Waltham, MA). Subsequently, volatiles were placed into Clarus 600 Gas Chromatography (PerkinElmer) (kept 40 °C for 2 min, raised to 180 °C at 6 °C /min, then raised to 270 °C at 15 °C /min, and kept 270 °C for 3 min) and Clarus 600T Mass Spectrometry (PerkinElmer) (250 °C and 230 °C for interface and ion source temperatures in respective). The type of chromatographic column was DB-5MS UI (30 m × 0.25 mm × 0.25 μm; Agilent Technologies, Santa Clara, CA). The ionization mode of mass spectrum was electron impact ion (EI), electron energy was 70 eV, and scan range was 30–500 m/z.