4. Conclusion
The results of this research confirm that near infrared spectroscopy
can be used for the qualitative as well as quantitative analysis
of compositions of sandalwood oils. Sandalwood oils of the same
species produced by various extraction methods, either developed
or under developed and collected from different regions (origin)
can be easily discriminated by the difference in their NIR spectra.
Near infrared spectroscopy assisted by multivariate chemometric
techniques viz. principal component analysis, hierarchical cluster
analysis or self organising map can be successfully applied to the
classification of sandalwood oils according to their quality. Quantification
of the constituents, especially adulterants if any, in sandalwood
oils is achieved by support vector machine regression with
proper combinations of data pretreatments.
In a nutshell, NIR spectroscopy technique has high potential to
determine the qualitative differences and to quantify simultaneously
the compositions of essential oils.