Comparison of three sample preparation methods on the recovery of volatiles from taheebo (Tabebuia impetiginosa Martius ex DC)

The volatile constituents of taheebo (the dried inner bark of Tabebuia impeliginosa Martius ex DC) were isolated by three methods: solvent-assisted flavour evaporation (SAFE); steam distillation under reduced pressure, followed by continuous liquid-liquid extraction (DRP-LLE); and high-flow dynamic headspace sampling (including closed-loop stripping) (DHS). The extracts were analysed qualitatively and quantitatively by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The masses of total volatile components recovered from 50 g taheebo by SAFE, DRP-LLE and DHS were 26.3 ± 2.0, 19.4 ± 1.0 and 1.2 ± 0.2 mg, respectively. The major constituents isolated with the SAFE method were 4-methoxyphenol (121.65 μg/g), 4-methoxybenzyl alcohol (96.49 μg/g), 1,2-propanediol (92.95 μg/g) and 4-methoxybenzaldehyde (31.33 μg/g). The DRP-LLC method yielded 4-methoxybenzaldehyde (64.54 μg/g), 4-methoxyphenol (42.30 μg/g), 5-(2-propenyl)-1,2,3-trimethoxybenzene (elemicin; 41.22 μg/g), and 1-methoxy-4-(1E)-1-propenylbenzene (trans-anethole; 39.16 μg/g) as major volatiles, while the main compounds recovered with the DHS method were 4-methoxybenzaldehyde (2.61 μg/g), 4-methoxyphenol (2.10 μg/g), 2-methyl-5-(1-methylethenyl)-2-cyclohexen-1-one (carvone; 1.71 μg/g) and 3,7-dimethyl-1,6-octadien-3-ol (linalool; 1.64 μg/g).