The analytical methods that are currently used for the quality control of natural product raw materials and products are gas chromatography (GC) and high performance liquid chromatography (HPLC). Although these methods are accurate, reproducible and highly selective, they are very time consuming, expensive and require a lot of sample preparation. This study aims to develop protocols based on vibrational spectroscopy techniques that will rapidly and non-destructively be used in the quality assessment/quality control of essential oils thereby eliminating costs and time required for routine chemical analysis.
• To identify and quantify the marker essential oil components in selected aromatic plants (Lippia javanica, Lippia scaberima, Lippia wilmsii, Lippia rehmannii, Tagetes minuta, Pelagonium graveolens, Salvia stenophylla, Eriocephalus punctulatus and A. betulina) using GC-MS.
• To perform MIR, NIR and Raman spectroscopy on both oil and leaf (powder) samples from the selected plants and compare spectra of the two sample types.
• To perform cluster analysis on the spectral data so as to determine variations within and between populations of the same species (qualitative characterization).
• To establish an MIR, NIR and Raman model/calibration to predict the quantities of marker components in both the oils and the leaves using GC-MS as the reference method.
• To compare the precision of the MIR, NIR and Raman models in predicting marker components in both the oils and the leaves.
• To analyse in situ the composition and distribution of essential oils in plant tissue (leaves) using hyperspectral imaging.
Principal supervisor: Prof AM Viljoen
Co-supervisors: Dr M Baranska