Vapor pressure measurements on linalool using a rapid and inexpensive method suitable for cannabis-associated terpenes†

Abstract

Vapor pressure (p^sat) data are needed to assess the potential use of terpenes as breath markers of recent cannabis use. Herein, a recently introduced gas-saturation method for p^sat measurements, known as dynamic vapor microextraction (DVME), was used to measure p^sat for the terpene (±)-3,7-dimethylocta-1,6-dien-3-ol, commonly known as linalool. The DVME apparatus utilizes inexpensive and commercially available components, a low internal volume, and helium carrier gas to minimize nonideal mixture behavior. In the temperature range from 314 K to 354 K, DVME-based measurements of the p^sat of linalool ranged from 81 Pa to 1250 Pa. With a measurement period of 30 min, the combined standard uncertainty of these measurements ranged from 0.0358·p^sat to 0.0584·p^sat, depending on temperature. The DVME-based measurements agree with a Wagner correlation of available literature data. We demonstrate that DVME produces accurate results for values of p^sat that are 200 times higher than in the DVME validation study with n-eicosane (C₂₀H₄₂). The oxidative stability of linalool was improved by the addition of 0.2 mass % of the antioxidant tert-butylhydroquinone.