Zb 5 fused silica capillary column

Three replicates of each sample were analyzed using a Hewlett-Packard Model 5890A gas chromatography (GC) instrument, equipped with a flame ionization detector and fitted with a 60 m × 0.25 mm, thickness 0.25 μm ZB-5 fused silica capillary column (Phenomenex); relevant technical details of the GC measurements were described previously [10 (link)]. The quantification of individual compounds was expressed as an absolute weight percentage compared to using an internal standard (2,6-dimethylphenol) and response factors. GC/mass spectrometry (GC/MS) analyses were carried out with an Agilent Technologies model 7820A, connected with an MS detector 5977E MSD (Agilent), using the same conditions and column described above. Monitoring of mass units was carried out at 10–900 AMU at 70 eV, while during identification (ID), peaks between 40–900 AMU were considered. Compound ID was done to compare their retention times with those of authentic samples and/or by comparing their mass spectra with those of published data [23 ,24 ] or based on interpretation of molecular EI-fragmentation.

Gas chromatography–mass spectrometry was carried out as previously described [14 (link)]: Shimadzu GCMS-QP2010 Ultra instrument, electron impact (EI) mode (electron energy = 70 eV), scan range = 40–400 atomic mass units, scan rate = 3.0 scans/s, and GC-MS solution software (Shimadzu Scientific Instruments, Columbia, MD, USA); ZB-5 fused silica capillary column, 30 m length, 0.25 mm internal diameter, 0.25 μm film thickness (Phenomenex, Torrance, CA, USA); He carrier gas, head pressure = 552 kPa, flow rate = 1.37 mL/min; injector temperature = 250 °C, ion source temperature = 200 °C, oven temperature program = 50 °C start, increased by 2 °C/min to 260 °C; 7% w/v solutions, 0.1 μL injections, split mode (30:1). Essential oil components were identified based on both their retention indices, which were determined by reference to a homologous n-alkane series, and their mass spectral fragmentation patterns available from the databases [17 ,18 ,19 ,20 ].

Each of the Callicarpa essential oils was analyzed by GC-MS using a Shimadzu GCMS-QP2010 Ultra (Shimadzu Scientific Instruments, Columbia, MD, USA) operated in the electron impact (EI) mode (electron energy = 70 eV), scan range = 40–400 atomic mass units, scan rate = 3.0 scans/s, and GC-MS solution software. The GC column was a ZB-5 fused silica capillary column (Phenomenex, Torrance, CA, USA) (30 m length × 0.25 mm internal diameter) with a (5% phenyl)-polymethylsiloxane stationary phase and a film thickness of 0.25 μm. The carrier gas was helium with a column head pressure of 552 kPa and flow rate of 1.37 mL/min. Injector temperature was 250 °C and the ion source temperature was 200 °C. The GC oven temperature program was programmed for 50 °C initial temperature, temperature increased at a rate of 2 °C/min to 260 °C. A 5% w/v solution of the sample in CH₂Cl₂ was prepared and 0.1 μL was injected with a splitting mode (30:1). Identification of the oil components was based on their retention indices determined by reference to a homologous series of n-alkanes (C₈-C₄₀), and by comparison of their mass spectral fragmentation patterns with those reported in the databases [60 ,61 ,62 ,63 ]. The percentages of each component in the essential oils are reported as raw percentages based on total ion current without standardization.