Analysis of homemade cannabis edibles by UHPLC–HRMS after standard addition method

With recent evolution of cannabis legalization around the world, cannabis edibles are booming, and determining their concentration in Δ9-tetrahydrocannabinol (Δ9-THC), the regulated psychoactive substance, remains a challenge for toxicology laboratories, which must prove whether the product has legal status or not. Cannabinoids are a large family of structurally similar and lipophilic molecules, requiring dedicated pre-analytical methods, as well as efficient chromatographic separation to differentiate cannabinoid isomers which are distinguished by their psychoactive properties and their legal status. Here, we present two independent cases of cannabis edibles, for which we performed analysis of homemade cannabis chocolate cakes and of the resins and herbs used for cooking. Quantitation was carried out with a new developed standard addition method, to avoid matrix effects and matrix-dependent calibration. Extraction by QuEChERs method, followed by targeted and non-targeted analysis by ultra-high performance liquid chromatography hyphenated to high resolution mass spectrometry (UHPLC-HRMS) allowed the identification of several phytocannabinoids, mainly Δ9-tetrahydrocannabinol (Δ9-THC), cannabidiol (CBD) and their acid precursors Δ9-THC acid (THCA) and CBD acid (CBDA). Δ9-THC was identified in significant concentrations (mg/g) in both edibles, even though one was prepared with CBD herb. This work highlights the need to analyze cannabis edibles, as well as the resins and herbs used in their preparation if it is homemade, and it proposes a reliable analytical method for toxicology laboratories.