Application of different chromatographic techniques to characterise wax by-products generated during cannabinoid extraction

Cannabinoid extraction during Cannabis processing produces a wax by-product which is currently underutilised, partially because the composition is poorly understood. This study applied both gas and liquid chromatography methods to characterise the major compounds present in the waxy by-product from commercial Cannabis processing. Two industrial wax by-products (wax A and wax B) were used as the feedstock for the characterisation, differing in both strain of Cannabis used and downstream processing conditions. The main classes quantified in the Cannabis waxes were cannabinoids, n-alkanes, fatty alcohols, fatty acids, sterols, and various terpenoids. The cannabinoid fraction was the most abundant fraction in both waxes, reporting a total fraction of 509.3 mg/g for wax A and 392.6 mg/g for wax B, on a solvent-free basis. For wax A the largest remaining wax compound class was the fatty acids, which reported a concentration of 172.2 mg/g, with linoleic acid being the most abundant at a concentration of 68.47 mg/g. The most abundant wax compound class in wax B was the n-alkanes at a concentration of 54.55 mg/g and the dominant species in that fraction was nonacosane (C29) with a concentration of 24.47 mg/g. It can be concluded that due to the high concentration of cannabinoids remaining in the wax even after processing, and their relative commercial value, recovery of the cannabinoids from the wax could form a potential valorisation application for the underutilised Cannabis wax by-product.