Qualitative GC–MS analysis was performed using an Agilent 7890A GC-system (Agilent Technologies, Santa Clare, CA, USA) equipped with an Agilent 7683B Series injector and paired with an Agilent 5975C Mass Selective Detector (single quadrupole). Hardware control, data acquisition and data handling were done using the Agilent Masshunter and Data analys® software version 10.0. Chromatographic separation was achieved using an Agilent J&W VF-5ms capillary column (40 m × 0.25 mm; 0.25 μm) with a temperature gradient that started at 80 °C, which was held for two minutes, followed by a gradient at a rate of 15 °C per minute until a temperature of 280 °C was reached. This temperature was held for 17 min, resulting in a total runtime of about 32.3 min. The injection volume was set at 1 μL and helium was used as carrier gas at a constant flow rate of 1.5 mL/min. The injector was operated in split mode (ratio 1:10) and the temperatures of the injection port, the ion source, the quadrupole and the interface were set at 250 °C, 230 °C, 150 °C and 280 °C, respectively. Mass data were recorded in full scan mode.
The mass spectra of the signals of interest were compared to the reference spectra in the eNIST20 Mass Spectral Library. A match factor above 85% was considered as reliable. If lower, the peaks were manually integrated to confirm the result.
The mass spectra of the signals of interest were compared to the reference spectra in the eNIST20 Mass Spectral Library. A match factor above 85% was considered as reliable. If lower, the peaks were manually integrated to confirm the result.