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Abstract

Methods for the identification of gas chromatographic
separated components of essential oils have been investigated.
The use of relative retention data was found to be of value
for identification only when known standards are available for
comparison. Tabulated Kovats indices, available from references,
were found to be unreliable for the identification of unknown
compounds. These techniques may be of value for preliminary
identification of some compounds, however it was found that
spectroscopic and chemical reaction data were necessary in order
to postively identify unknown compounds.
Combined gas chromatography - mass spectrometry computer
techniques enabled the rapid identification of the majority of
compounds present in these complex mixtures. Compounds identified
by this technique were found to be in agreement with many previously
identified by retention data. There were limitations in the
identification of compounds with similar spectra and the spectra
of unknown compounds not being included in the data base.
Where other spectroscopic data was necessary for identification
purposes, an off-line gas chromatographic sampling device was
constructed which enabled the collection of nanogram amounts of
compounds eluting from a gas chromatographic column. Compounds
collected this way were able to have their Raman spectra recorded
without any further sample manipulation. The technique was also
used for the recording of infrared, and nuclear magnetic resonance
spectra enabling positive identification of some compounds.
Techniques of reaction gas chromatography mass spectrometry
were developed. Hydrogenation techniques were found useful for the determination of the number of double bonds in a compound whilst
carbon skeleton chromatography - mass spectromatry was used for the
identification of the hydrocarbon skeleton of unidentified compounds.
Subtraction gas chromatography enabled the tentative identification
of the alcohol functional group in some compounds.
It was concluded that, due to the complex nature of the essential
oils investigated, a single technique is not available that enables
complete identification of all components. A combination of all
these methods must often be used for the complete identification of
components in essential oils.

Item Type:	Thesis - Coursework Master
Authors/Creators:	Dineen, Robert Denison
Copyright Holders:	The Author
Copyright Information:	Copyright 1985 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Includes bibliography
Item Statistics:	View statistics for this item

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