Isolation and Characterization of Impurities in Commercially Marketed Δ8-THC Products

Qualitative analysis of several commercial products containing Δ8-tetrahydrocannabinol (Δ8-THC) as a major component using GC-MS resulted in the identification of several impurities along with Δ8-THC. In an attempt to isolate and identify these impurities, a commercial Δ8-THC distillate was selected for the isolation work. Eleven impurities were isolated using a variety of chromatographic techniques, and their chemical structures were determined. These include Δ4,8-iso-tetrahydrocannabinol (1), Δ4-iso-tetrahydrocannabinol (2), Δ8-cis-iso-tetrahydrocannabinol (3), 4,8-epoxy-iso-tetrahydrocannabinol (4), 8-hydroxy-iso-tetrahydrocannabinol (5), 9β-hydroxyhexahydrocannabinol (6), 9α-hydroxyhexa-hydrocannabinol (7), iso-tetrahydrocannabifuran (8), cannabicitran (CBT, 9), olivetol (10), and Δ9-THC (11). The chemical structures of the purified compounds were determined using several spectroscopic methods, including 1D (1H, 13C, and DEPT-135) and 2D (COSY, HMQC, HMBC, and NOESY) NMR, LC-MS, and GC-MS. Other naturally occurring cannabinoids and impurities were also identified in GC-MS chromatograms but were not isolated. These were cannabidiol (CBD, 12), cannabinol (CBN, 13), hexahydrocannabinol (HHC, 14), and Δ8-tetrahydrocannabivarin (Δ8-THCV, 15). The chemical structure of Δ8-THCV (15), for which a standard was not available, was confirmed by partial synthesis and NMR analysis. This is the first report for many of the above compounds as well as Δ8-THCV as impurities in Δ8-THC products.