Determination of Δ9-THC, THCA, Δ8-THC, and total Δ9-THC in 53 Smokable Hemp Plant Products by Liquid Chromatography and Photodiode Array Detection

Published

January 8, 2024

Author(s)

Walter Brent Wilson, Aaron Urbas, MARYAM ABDUL-RAHMAN, Arianna Romares, Ewelina Mistek-Morabito

Abstract

The passage of the 2018 Farm Bill has led to an estimated value of $824M for hemp production in the United States (US) in 2021 with an approximately 76% of it focused on floral hemp that is used to produce hemp-derived finished products such as smokable hemp (e.g., manicured roll your own or cigarettes). As a result, forensic laboratories have seen a significant increase in confiscated cannabis samples but lack access to reliable analytical methods for differentiation between hemp and marijuana in seized cannabis samples. Forensic laboratories were required to perform confirmatory test for the presence of Δ9-THC in seized samples prior to the 2018 Farm Bill; however, the new legislation defined hemp as cannabis containing 0.3% or less of decarboxylated-Δ9-THC. In response, the National Institute of Standards and Technology (NIST) have been developing and evaluating analytical methods to provide forensic scientist the tools necessary. In this article, 53 smokable hemp products were analyzed for Δ8-THC, Δ9-THC, THCA, and total Δ9-THC by a previously established liquid chromatography with photodiode array detection (LC-PDA) method using a methanol extraction procedure previously approved by an AOAC Expert Review Panel. One of the reasons LC-PDA is the most common analytical technique used in the cannabis industry is that it permits the calculation of total Δ9-THC, which incorporates Δ9-THC and its acidic precursor tetrahydrocannabinolic acid (THCA) that decarboxylates into Δ9-THC. The results summarized here were to further demonstrate the accuracy and precision of the LC-PDA method for smokable hemp samples with total Δ9-THC values at the federal limit of ≤ 0.3%; however, approximately 93% of the samples were determined by NIST to have a total Δ9-THC value above this limit. All samples were being sold as federally legal hemp products with claimed Δ9-THC values below 0.3% despite their website providing Certificate of Analysis (COA) with total Δ9-THC values ≥ 0.3%. Comparisons were made between NIST and the manufacturer's COA mass fraction values for 22 samples with overlapping uncertainties for ≈ 55% of total Δ9-THC, ≈ 68% of THCA, and ≈ 18% of Δ9-THC. These poor comparisons result from either inaccurate analytical measurements by the contract testing laboratories, homogeneity issue across the batch of products, long-term storage conditions, and/or manufacturer's not updating their COA over the lifetime of the product.

Citation

Forensic Chemistry

Volume

37

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.forc.2024.100550

Local Download

Keywords

Hemp, Cannabis, Marijuana, Cannabinoids, Δ-9-Tetrahydrocannabinol, Liquid Chromatography

Citation

Wilson, W. , Urbas, A. , ABDUL-RAHMAN, M. , Romares, A. and Mistek-Morabito, E. (2024), Determination of Δ9-THC, THCA, Δ8-THC, and total Δ9-THC in 53 Smokable Hemp Plant Products by Liquid Chromatography and Photodiode Array Detection, Forensic Chemistry, [online], https://doi.org/10.1016/j.forc.2024.100550, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935910 (Accessed November 21, 2024)