Accurate THC Determinations in Seized Cannabis-derived Finished Products for Forensic Laboratories

Since the 1970s, Cannabis plant (marijuana and hemp) and its psychoactive constituent, Δ9 – tetrahydrocannabinol (Δ9-THC), have been classified as Schedule I controlled substances. Drug scheduling has directed the forensic testing approaches, as qualitative confirmation of the presence of Δ9-THC was sufficient to demonstrate possession of a controlled substance. Currently, marijuana and Δ9-THC remain on the controlled substances list, although medical marijuana is legal in 36 states and recreational marijuana is legal in 17 states. In 2020, the legal Cannabis market in the United States had gross sales of $18.3B. Much of this can be attributed to the passage of the 2018 Farm Bill that defined hemp as Cannabis plant or finished products containing 0.3% or less of decarboxylated-Δ9-THC (total THC) and removed hemp from the controlled substances list. As a result, the legal Cannabis market exploded with a wide range of finished products. By the end of 2020, Cannabis plant products only made up 32% of the total sales while edibles/ingestibles and vape cartridges each represent 26 %.

        Forensic laboratories are now required to quantify the level of total THC not only in seized Cannabis plant, but also finished products as illegal or legal materials. Prior to 2019, almost no forensic laboratories had experience in or were accredited to perform quantitative drug analysis. The GC-MS approach commonly being implemented in forensic laboratories use an internal standard of 4-androsten-3,17-dione. During sample injection on the GC, the carboxylic acid functional groups of the acidic cannabinoids are decarboxylated to their neutral forms under the high temperatures of the GC inlet. However,  4-androsten-3,17-dione  doesn’t account for the decarboxylation rate. To overcome these limitations, NIST will use isotopically-labeled internal standards of Δ9-THC-d3 and THCA-d3 providing a total THC-d3 internal standard.   

      The overall goal of this project is to provide federal, state, and local forensic laboratories with validated simple, robust, and cost-effective extraction and sample clean-up procedures combined with ID-GC-MS, LC-PDA, IR, and Raman methods for the confident differentiation of seized Cannabis-derived finished products such as extracts, oils, vape liquids, edibles. To help facilitate technology transfer, NIST has formed a collaboration with Montgomery County Police Department (MCPD) and Maryland State Police crime labs to provide critical evaluation of the new procedures. In addition, the collaboration with MCPD has permitted the transfer of adjudicated seized Cannabis samples for method validation.