Pattern Recognition Methods for Discrimination of Essential Oils (Rose Oils) by Their Gas Chromatograms

It is possible to distinguish between essential oils of the same type and their mixtures by analysing their gas chromatograms using a pattern recognition method. An approach for the selection of peaks used in the calculation of the differentiation criterion is demonstrated. The accuracy and scope of the method are demonstrated using sixteen rose oil samples (genuine or blended) and five-fold repeat analyses of the same rose oil. The selectivity of this method permits an objective confirmation of the differences or similarities in the composition of the compared essential oils.

Essential oils are used mainly in the perfumery, cosmetic and food industries. Their market prices depend primarily on their quality as determined by organoleptic tests. This assessment however, because of its subjective nature, cannot be used with sufficient confidence in solving technological, commercial or other issues, Moreover, the physiochemical indices determined by conventional chemical methods, applied in detecting blending or adulteration, show too much variation to be reliable when small deviations are concerned.

Better results can be achieved when applying chromatographic and spectroscopic methods. Visual comparison of gas chromatograms of different types of essential oils normally is sufficient for distinguishing between them. However, such evaluations cannot be considered as reliable when a great number of samples of specific types of oils or oil mixture are involved.

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