Production of Delta-9-Tetrahydrocannabinol Reference Standard from Cannabis sativa L.

Abstract

Introduction and objectives: Thailand's cannabis policy, which permits the medical use of cannabis, has led to increased production and research of cannabis-derived products. Ensuring the quality control of cannabis extracts and products to meet safety standards and legal requirements necessitates the use of a standard substance, delta-9-tetrahydrocannabinol (delta-9-THC), for comparative analysis in quantifying active compounds. The Bureau of Drug and Narcotic, Department of Medical Sciences, has undertaken the production of delta-9-THC reference standard to support national policy and reduce the ongoing reliance on imported reference standards.

Methods: Delta-9-THC was extracted and isolated from the inflorescence of cannabis using supercritical fluid extraction (SFE) with a suitable ratio of carbon dioxide to ethanol. The resulting extract was further purified using supercritical fluid chromatography (SFC) to obtaining delta-9-THC. The identity of the compound was confirmed through IR spectroscopy, mass spectrometry, and ¹H-NMR spectroscopy, and purity was analyzed using high-performance liquid chromatography (HPLC) prior to its establishing as a Department of Medical Sciences reference standard.

Results: The application of SFE with a carbon dioxide to ethanol ratio of 95:5 suitably produced a cannabinoids-rich extract. Subsequent purification of cannabinoids-rich extract via SFC achieved delta-9-THC with 99.4% purity, calculated on the as is basis, obtaining a yield of 0.6%. The produced delta-9-THC reference substance, formulated in methanol solution, adhered to ISO 17034:2016 standards for reference material production. Stability assessments indicated that the substance maintained its integrity when stored at 2–8°C over a three-year period. The homogeneity studies demonstrating uniformity throughout production batch. The certified concentration with associated uncertainty of the standard was determined to be 0.9303 ± 0.0792 mg/mL.

Discussion: The use of SFE and SFC under developed conditions enabled the selective isolation of delta-9-THC from other cannabinoids, achieving >99% purity. This method presents minimal environmental and health impacts compared to traditional organic solvents.

Conclusion and recommendations: The produced standard substance can be utilized for analyzing delta-9-THC amounts in cannabis plants, extracts, and products, ensuring the quality of domestically produced medical cannabis products. Furthermore, it serves as a resource for research, efficacy testing, toxicity assessment, and the determination of active ingredient dosages in future medical applications.