Introduction. Essential oils (EO) and their separate components are widely used in medicine, the food industry, fragrances, etc. Nevertheless, problems related to their standardization, quality factors, and authenticity remain unsolved for practical application of EO. In contrast with chemical drugs, which are relatively easily standardized with respect to the quantity and composition of pharmacologically active components, the quality of phytopreparations is determined mainly by the seasonal accumulation dynamics of physiologically active substances in the plants and the conditions for collecting, drying, storing, and processing the plant raw material. Furthermore, plants frequently exhibit significant polymorphism within a genus. The combination of the aforementioned factors in extreme instances can produce pronounced toxicity of EO owing to excessive accumulation of separate components, one of which is pulegone [1,2].These problems can be solved by using instrumental methods that provide reliable characterization of systems with complicated compositions. In fact, gas-liquid chromatography (GC) and high-efficiency liquid chromatography (HPLC) with various types of mass-spectrometric detection have recently been used widely to determine EO compositions [3]. However, although there are several advantages (high sensitivity, good resolving power), these methods also typically have serious shortcomings. Thus, a necessary condition for identification and quantitative determination of pure components is the availability of standard markers or at least databases of mass spectra for the corresponding instrument modification. Also, GC can detect only relatively volatile and rather thermally stable components. HPLC analysis requires large volumes of expensive eluents. Furthermore, peroxide oxidation is facilitated with free access to oxygen, especially in light or at elevated temperature. This increases the concentration of aldehydes, acids, peroxides, and oxides and accelerates degradation of the components. This complicates the chromatographic separation. All this necessitates a search for and the introduction into practice of new, reliable, and fast methods for characterizing EO samples. Along these lines, high-resolution NMR spectroscopy deserves serious attention. Modern spectrometers have high sensitivity and can analyze complicated compositions in different samples within a short (minutes) time with reliable results. Special sample preparation is not required. This shortens significantly the analysis time compared with chromatographic methods.
