Use of Headspace Solid Phase Microextraction and GC-MS for Qualitative and Quantitative Analysis of Terpenes in Cannabis

Klaus Buckendahl, Merck/Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany (klaus.buckendahl@merckgroup.com)
Katherine Stenerson, Milliporesigma, Bellefonte Pa, Usa
Michael Halpenny, Milliporesigma, Bellefonte Pa, Usa
Leonard Sidisky, Milliporesigma, Bellefonte Pa, Usa
Lisa McCombie, Milliporesigma, Bellefonte Pa, Usa

Terpenes are hydrocarbons synthesized by some plants. They consist of isoprene units joined in a “head-to-tail” configuration, and classification is based on the number of these units in the structure. Configurations can be cyclic or open, and can include double bonds, and hydroxyl, carbonyl or other functional groups. They are contained in the essential oils derived from plants such as cannabis, and often impart characteristic aromas to the plant and/or oil. The distinct aromas associated with different strains of cannabis are a result of varying terpene profiles. Terpene testing is therefore done on cannabis to determine content in association with strain identification and/or therapeutic use.

A common approach for terpene analysis of cannabis involves a solvent extraction followed by GC-FID analysis. In this application, headspace-solid phase microextraction (HS-SPME) combined with GC/MS was used to profile some of the terpenes present in dried cannabis. Retention indices and MS spectra were used to identify 45 different compounds. HS-SPME was then used to quantitate several select terpenes.  Method accuracy and precision were determined using low terpene content cannabis spiked at known levels with alpha-pinene, d-limonene, and linalool. The results obtained were compared to a conventional liquid extraction method using GC/FID for analysis. Both methods yielded similar accuracy and reproducibility; however the HS-SPME method was simpler, faster, and did not require the use of organic solvents. In addition, the sampling was non-destructive.