| Summary: | A comparative study was undertaken of different extraction methods for the isolation of
volatile organic compounds from Murraya koenigii (curry leaf plant). The techniques
studied included the traditional methods of extraction, namely, Soxhlet and solvent
extraction as well as steam distillation. The solvent–free extraction techniques of
headspace analysis and headspace solid phase micro-extraction (HS-SPME) were also
investigated. In the evaluation of SPME, two different fibre coatings,
poly(dimethylsiloxane) and poly(acrylate), were compared. Preliminary work to
determine the effect of extraction parameters, such as extraction time, was carried out.
The volatile oils in the fresh leaves of Murraya koenigii were isolated by the above-mentioned
extraction methods and analysed by gas chromatography-mass spectrometry.
The main aroma contributing compounds were identified by comparison of their
retention times with those of standards and their mass spectra with those of known
compounds contained in the National Institute of Science and Technology Standard
Reference Database 1A (NIST 98).
The essential oil contained mainly terpenes: monoterpene and sesquiterpene
hydrocarbons. The constituents were identified and only the five selected analytes of
interest, a-pinene, β-pinene, a-phellandrene, β-caryophyllene and a-caryophyllene
were quantified in three of the methods, namely solvent extraction, soxhlet extraction
and steam distillation.
From the quantitative determination of the compounds of interest, steam distillation
favoured the extraction of β-caryophyllene. The solvent and Soxhlet extractions
showed no significant differences between the quantities obtained for a- and β-
caryophyllene. The steam distillation and Soxhlet methods showed similar quantities of
a-caryophyllene extracted. The extraction of the monoterpenes, a-pinene, β-pinene, and
a-phellandrene, was favoured by the Soxhlet method of extraction. Quantification was
difficult with HS-SPME and headspace analysis.
Headspace analysis proved effective in the detection of the very volatile analytes.
Headspace-SPME combined with GC-MS was found to be suitable for the identification
of both monoterpenes and sesquiterpenes of M. koenigii.
From this study, solvent extraction and Soxhlet extraction were found to be superior to
the other methods studied for the characterisation and quantitation of the volatile
organic compounds in essential oils of Murraya koenigii. === Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.
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