New Analytical Method Successfully Quantifies Trace Cannabinoids in Honey
The cannabis extraction industry is well into its growth spurt, having birthed an entire galaxy of new products for recreational and medicinal consumers to use and enjoy. However, it is occasionally Mother Earth who shows herself to be the more interesting (if not more potent) extractor amongst us.
With the proliferation of fiber-type Cannabis sativa L. (hemp) cultivation across the world, it is interesting, but not entirely unsurprisingly, to find out that nature’s most prolific pollinators have been ‘extracting’ cannabinoids from hemp pollen and incorporate them directly into their honey supply. And while hemp varieties have considerably lower overall cannabinoid content compared to cannabis cultivars, and are mandated by law to have basically no THC at all (<0.2-0.3% by weight depending on where you are), recent data shows that honeybees who forage on hemp incorporate some cannabinoids into their honey after all.
A study by Italian scientists at the University of Modena recently developed a new analytical method by which to test for trace cannabinoid content in bee products.  Honey, with its high sugar and flavonoid content, represents a particularly difficult matrix from which to quantify or extract cannabinoids using standard, previously described techniques. The trace (meaning extremely low) cannabinoid content in these natural products also compounds this difficulty.
This presents the rationale for the development of a novel quantification technique. In this study, Brighenti et al extracted cannabinoids from honey using the QuEChERS sample preparation technique, with water as the homogenizing agent at 40°C and ammonium acetate (CH3COO-NH4) mixed with acetonitrile at a 1:1 ratio as the final carrier solvent. Then, the cannabinoid content was quantified using a type of high-performance liquid chromatography called reverse-phase HPLC, in which water-soluble (hydrophilic) molecules are detected (eluted) first, and fat-soluble (hydrophobic) molecules elute last. The amount of time a molecule spends in the RP-HPLC column (the retention time) is therefore directly proportional to its hydrophobicity.
When comparing their results to matrix standards generated by dissolving known amounts of pure cannabinoid isolates in cannabinoid-free acacia honey, the researchers detected cannabidiol (CBD), cannabidiolic acid (CBDA), cannabigerol (CBG), and cannabigerolic acid (CBGA) at very low concentrations, but at ratios similar to those found in CBD-type hemp pollen similar to the species the honeybees foraged on.
Although the concentration of cannabinoids found in this study was extremely low, with total cannabidiol (CBD + CBDA) content being less than 50 ng/g, or roughly 23 mg/lb, the discovery of this new technique will allow scientists to monitor the amount of cannabinoids in honey, and may provide inspiration for ways to analyze other comparably difficult matrices as well.
- Brighenti, V. et al. “Development of a new method for the analysis of cannabinoids in honey by means of high-performance liquid chromatography coupled with electrospray ionisation-tandem mass spectrometry detection”. J Chromatography A. 2019; 1597: 179–186 [Times cited = 0, Journal impact factor = 4.169].
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