P. Marriott et al., High resolution essential oil analysis by using comprehensive gas chromatographic methodology, FLAV FRAG J, 15(4), 2000, pp. 225-239
The new technique of comprehensive gas chromatography (GC x GC) is applied
to the analysis of Vetiver essential oil, and the complex nature of the oil
components is readily displayed in a two-dimension separation space. The G
C x GC method involves the use of two directly coupled columns, with a cryo
genic modulation system at their confluence; this allows coeluting peaks fr
om the first column to be zone compressed and pulsed rapidly into the secon
d column and separated. Greater sensitivity of detection is also obtained.
Results show that the earlier eluting components from the gas chromatograph
y analysis have similar chemical nature in respect of component polarity, b
eing of low-to-moderate polarity. Later eluting compounds appear to be more
polar, and are presumably of an oxygenated nature. Many of these show exte
nsive co-elution, with up to 6-8 overlapping compounds on the first column.
These results clearly demonstrate that the complexity of essential oils is
much greater than that which might be suspected from single column GC anal
ysis, and also suggest that GC-MS analysis with peak deconvolution capabili
ties will still probably not be able to adequately identify the interfering
components. With GC x GC, minor constituents in the presence of larger com
ponents may still be well characterized and quantitated, and from the chrom
atographic retention patterns their chemical nature might be indicated; thi
s would be aided by establishing the retention behaviour of known compounds
. Copyright (C) 2000 John Wiley & Sons, Ltd.