Authentication of essential oils

Essential oils are commonly defined as complex mixtures of flavor and fragrance substances originating from plants. The authenticity of natural compounds is an important topic for the flavor and fragrance industry because of legal or commercial aspects. Over the last 15 years stable isotope analysis has become the most important tool for authenticity testing of non-chiral compounds. The analysis of enantiomeric purity is well-known as an efficient possibility for the authenticity control of chiral compounds. It is of great interest to check whether it is possible to detect the blending with synthetic substances or with isolates from other essential oils. In this paper we present examples for the use of both methods for authentication of laurel leaf (a-terpinyl acetate), oregano (carvacrol), ylang ylang (p-cresyl methyl ether, benzyl acetate) and sandalwood oil (cis-α-santalol). This publication demonstrates the merits of enantioselective capillary GC and isotope ratio mass spectrometry (IRMS), coupled on-line with capillary GC for the authentication process.