Characterization of chemotype-dependent terpenoids profile in cannabis by headspace gas-chromatography coupled to time-of-flight mass spectrometry.

Abstract

A headspace method called full evaporation technique (FET) coupled to capillary gas chromatography with a mass detector operating in time-of-flight mode (HS-GC/MS-TOF) was developed to characterize the volatile components, especially the terpene fraction, in Cannabis sativa L. inflorescences. This analytical approach allows to reach a high equilibration temperature, that was able to obtain a complete quantification of the volatile components, providing simple sample preparation, specific qualitative detection, high sensitivity, a precise and accurate quantitative determination. The method was applied to 20 cannabis THC-dominant (I) and 13 CBD-dominant (III) chemotypes. The obtained results were then compared with a series of standard solutions consisting of 35 terpenoids and the mass spectra present in a computer library (NIST). The method has an accuracy of more than 90 % and a limit of detection of 5 ppm for all analytes. The main terpenoids in cannabis are namely (% Chemotypes III vs. I of the total terpene content): β-Caryophyllene (25 vs. 19.3), β-Mircene (18.2 vs. 20.0), Terpinolene (12.1 vs. 7.0), α-Humulene (6.5 vs. 8.5), D-Limonene (6.2 vs. 7.2), α-Pinene (5.8 vs. 4.9), β-Pinene (5.0 vs. 5.8) and cis-β-Ocimene (4.3 vs. 5.2), whose presence is confirmed in both plant chemotypes and account for more than 80 % of the total terpenoids amount. The terpenoids which can clearly distinguish the chemotype are α-Terpineol, Linalool, DL-Menthol, α-Cedrene, and Borneol. This application provides important data on the secondary volatile components of the plant, which may be useful for a better understanding of the therapeutic properties of the cannabis phyto-complex. It gives the possibility of establishing the aroma profile of different Cannabis batches, allowing possible similarities between samples and identifying any artificial adulteration such as hexyl butyrate ester and it provides the opportunity to highlight some target compounds characteristic of the different chemotypes.