Accurate THC Determinations in Seized Cannabis Samples for Forensic Laboratories

With the passage of the 2018 Farm Bill, forensic laboratories have been forced to start differentiating seized Cannabis samples as either legal hemp or illegal marijuana; however, most forensic laboratories are currently lacking reliable extraction protocols and analytical methods for this purpose. Historically, forensic laboratories have only performed a series of qualitative measurements: macro- and microscopic identification of plant features, colorimetric test for presence of THC, and confirmation of Δ9-tetrahydrocannabinol (Δ9-THC) by gas chromatography-mass spectrometry (GC-MS). The new legislation declassified hemp as a Scheduled 1 drug substances and defined it as Cannabis containing 0.3 % or less of decarboxylated-Δ9-THC (total THC). As a result, forensic laboratories are now required to quantify the level of total THC in seized evidence to distinguish as either hemp or marijuana.

The objective of this project is to provide forensic laboratories with the necessary analytical tools to confidently make these measurements through simple, robust, and cost-effective analytical methods. This effort will focus on the development of isotope dilution GC-MS methods, extraction protocols, a single laboratory validation study, and evaluations of benchtop and portable infrared spectrometers. GC-MS is generally favored in forensic laboratories because of short separation times and no solvent consumption. Existing qualitative GC-MS approaches are amenable to quantitative measurements with specific analytical modifications to sample preparation protocols, addition of isotopically labeled internal standards (i.e., Δ9-THC-d3), and data collection mode from full scan to single ion monitoring mode for quantitation of m/z 299 ion.

After method completion, this proposal includes a technology transfer focus from NIST to the federal, state, and local forensic laboratories through standard operating procedures, training modules, webinars, and scientific publications. To help facilitate the transfer, NIST has formed a collaboration with Montgomery County Police Department (MCPD) and Maryland State Police (MSP) crime labs. The collaboration with MCPD has permitted the transfer of 125 adjudicated seized Cannabis samples for method validation. NIST will use the collaboration with MSP to allow for a critical evaluation of the new analytical methods to ensure their applicability to meet forensic laboratory needs.