Agilent 7890a 5975 gc ms system

The DHE samples were analysed using Agilent 7890A-5975 GC-MS system (Agilent Technologies Co. Ltd., Palo Alto, CA, USA) equipped with an automated thermal desorber (Turbomatrix ATD), using a Supelcowax 10 column (60 m × 0.25 mm i.d., 0.5 µm film thickness, from Sigma, Poole, UK) and a DB 5 column (60 m × 0.25 mm i.d., 1 µm film thickness from J&W Scientific, Agilent, Palo Alto, CA, USA) under instrumental conditions described by Methven et al. (2007) . The identification of the compounds was based on the comparison of their mass spectra with spectra from the NIST 11 Mass Spectral Database (NIST/EPA/MSDC, 1992). The linear retention index (LRI) was calculated for each volatile using the retention times of a series of C5-C25 n-alkanes. The identities of most of the volatiles were confirmed if their mass spectra and LRI matched those of authentic compounds run under the same analytical conditions in our laboratory. Volatiles were considered as tentatively identified by matching their mass spectra with the references mass spectra in the NIST mass spectral library, and by comparison of their LRI to the NIST database (NIST Chemistry WebBook, 2017). Volatiles were semi-quantitatively determined by comparison of the peak areas against those of the internal standard using a response factor of 1 for each compound.

The DHE samples were analysed using an Agilent 7890A-5975 GC-MS system (Agilent Technologies Co. Ltd., Palo Alto, CA, USA) equipped with an automated thermal desorber (Turbomatrix ATD), using a DB 5 column (60 m × 0.25 mm i.d., 1 µm film thickness from J&W Scientific, Agilent, Palo Alto, CA, USA) under instrumental conditions described by Chen et al. 7 The identification of the compounds was based on the comparison of their mass spectra with spectra from the NIST 11 Mass Spectral Database. 9 The linear retention index (LRI) was calculated for each volatile using the retention times of a series of C5-C25 n-alkanes. The identities of most of the volatiles were confirmed if their mass spectra and LRI matched those of authentic compounds run under the same analytical conditions in our laboratory. Volatiles were considered as tentatively identified by matching their mass spectra with the reference mass spectra in the NIST mass spectral library, and by comparison of their LRI to the NIST Chemistry WebBook database. 10 Volatiles were semi-quantitatively determined by comparison of the peak areas against that of the internal standard using a response factor of 1 for each compound.