a study of the quality of a local herbal tea and volatiles of parinari ...

3.10 Identification of volatile constituents
3.10.1 GC and GC-MS conditions for SPME
The head-space volatiles were analysed by GC-MS (Agilent 6890N GC system coupled
directly to a 5973 MS). The splitless injection was carried out manually at 24.79 psi and
an inlet temperature of 250 0 C. The GC system equipped with a HP-Innowax
polyethylene glycol column (60 m x 250 µm i.d., 0.25 µm film thickness was used. The
oven temperature program was 60 0 C for the first 10 min, rising to 220 0 C at a rate of 4
0 C/min and held for 10 min and then rising to 240 0 C at a rate of 1 0 C / min. Helium was
used as a carrier gas at a constant flow rate of 1.2 ml/min. Spectra were obtained on
electron impact at 70 eV, scanning from 35 to 550 m/z. n- Alkanes (C6-C24) were used
as reference points in calculation of retention indices (RI). Component identifications
were made by comparing mass spectra and retention indices. Library searches were
carried out using NIST, Mass Finder, Flavour and the Baser library of essential oil
constituents by comparing mass spectra and retention indices (Viljoen et al., 2008).
3.10.2 GC and GC-MS conditions for hydrodistillation, steam distillation
and CFMD samples
Extracts from hydrodistillation, steam distillation and cold finger molecular distillation
were analysed using the following conditions: A GC-MS (Agilent 6890N GC system
coupled directly to a 5973 MS) was used. A volume of 1µl was injected (splitless) using
an autosampler at 24.79 psi, an inlet temperature of 250 0 C. The GC system equipped with
a HP-Innowax polyethylene glycol column (60 m x 250 µm i.d x 0.25 µM film thickness)
was used. The ion source (electron impact ionization and the GC-MS interface
temperature) was 260 0 C. The oven temperature program was 60 0 C for the first 10 min,
rising to a rate of 4 0 C/min and held for 10 min and then rising to 240 0 C at a rate of
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