Integrated comprehensive two-dimensional gas-chromatographic and spectroscopic characterization of vetiveryl acetates: Molecular identifications, quantification of constituents, regulatory and olfactory considerations

Abstract

Vetiveryl acetate is a common ingredient of the perfume industry highly prized by perfumers for its crisp vetiver note and thus often used in high-end perfume compositions. Vetiveryl acetate is currently manufactured from vetiver oil by means of various industrial processes that result in the conversion of the main vetiver alcohols into their corresponding acetates. Despite being used for decades as perfume ingredient, vetiveryl acetate has barely been studied in the past, therefore its chemical composition is poorly documented. While vetiveryl acetate is currently under investigation by regulation authorities, it was crucial to fill this gap of knowledge. We report here the first detailed investigation of different types of vetiveryl acetates, covering analytical, regulatory, and olfactory aspects. This study is based upon an integrated analytical methodology involving a full array of gas chromatographic techniques and spectroscopic/spectrometric methods. The principal objective was the identification of the main ester constituents contained in different samples of vetiveryl acetate, as well as linking their chemical composition with their manufacture process. Among the major esters detected in all samples, 23 ester constituents were either isolated by capillary preparative-gas chromatography or synthesized in order to provide their complete spectral characterization. The quantification of constituents in both commercial and laboratory-made vetiveryl acetates was carried out by internal calibration using comprehensive two-dimensional-gas chromatography and predicted relative response factors. The generated set of analytical data permitted to explore both the regulatory aspects and the olfactory properties associated with the substance. The manufacture of vetiveryl acetate modulates the initial scent of vetiver essential oil by suppressing the notes brought by the main fragrant alcohols. While the impact of undesired odorant molecules such as phenol derivatives and geosmin is lowered, the major odour-active ketones such as khusimone, ziza-6(13)-en-3-ones, and the two vetivones develop their own odor characters in vetiveryl acetate.