Assessing the Detectability of Cannabinoid Analogs (Delta-8 THC, Delta-10 THC and CBD) and their Major Metabolites in Six Commercial Cannabinoid Urine Screening Kits

Background: There has been an exponential surge in the presence and use of cannabinoids since the federal legalization of hemp (Agricultural Improvement Act of 2018), which involves the legalization of medical use, adult recreational use, and decriminalization of cannabis in several states. This growth is not only attributed to ∆9-tetrahydrocannabinol (∆9-THC) and cannabidiol (CBD), the most abundant phytocannabinoid components of cannabis and hemp, respectively, but with many other emerging THC analogs. Structurally, these analogs are similar to ∆9-THC, yet very little information is available about their potency and even less information is available regarding their detectability using commercially available cannabinoid screening kits. Due to their structural similarity, current ∆9-THC immunoassay screening methods may be able to detect these emerging cannabinoid analogs. Objectives: To evaluate the ability of six commercially available homogeneous urine cannabinoid screening kits to detect ∆8-THC, CBD and their major metabolites, and ∆10-THC chiral analogs at 50 ng/mL and 20 or 25 ng/mL cutoff concentrations. Methods: Six urine immunoassay kits (Abbott Cannabinoids – Abbott Diagnostics, LZI Cannabinoids (cTHC) Enzyme Immunoassay – Lin-Zhi International, DRI® Cannabinoid Assay and CEDIA™ THC – Thermo Fisher Scientific, ONLINE DAT Cannabinoid II – Roche Diagnostics, and Syva EMIT®II Plus – Siemens Healthineers) were evaluated at two different cutoff concentrations: 50 ng/mL and 20 or 25 ng/mL. The analysis was performed on an Abbott Architect Plus c4000 (Abbott Diagnostics). ∆8-THC, CBD, olivetol and their major metabolites, and ∆10-THC chiral analogs were evaluated. The limit of detection was evaluated by preparing each analyte at 20, 50, 100, and 1000 ng/mL in urine. Samples were analyzed at both cutoff concentrations to determine if the analyte could be detected at one or both cutoff(s). Analytes not detected at 1000 ng/mL for a cutoff were considered not detectable. If detected, the appropriate concentration was used as the decision point to determine the precision at the immunoassay’s cutoff. Precision was assessed using three QC pools of the analyte prepared at -50%(QCN), the decision point, and +100%(QCP), which were analyzed in five different runs (n=3) along with the respective immunoassay’s control materials. The total mean (n=15), standard deviation (SD), and percent coefficient of variation (%CV) were calculated for each QC concentration. A decision point was considered valid if the %CV for the QC was ≤20% for each concentration, and the total mean of the QCN and QCP ±2SD did not overlap the mean of the decision point. Results: The minimum detectable concentration for ∆8-THC was 200 ng/mL using the 50 ng/mL cutoff by Abbott, DRI, LZI, and SYVA. The minimum detectable concentration for ∆8-THC was 100 ng/mL using the 20 or 25 ng/mL cutoff by Abbott(20), DRI(20), LZI(25), and SYVA(20). ∆8-THC was not detected at either cutoff by CEDIA or ROCHE. The minimum detectable concentration for 11-OH-∆8-THC and 11-COOH-∆8-THC was 100 ng/mL using the 50 ng/mL cutoff by Abbott, CEDIA, DRI, LZI, ROCHE, and SYVA. The minimum detectable concentration for 11-OH-∆8-THC and 11-COOH-∆8-THC was 50 ng/mL using the 20 or 25 ng/mL cutoff by Abbott(20), CEDIA(25), DRI(20), LZI(25), ROCHE(20), and SYVA(20). The minimum detectable concentration for 6-OH-CBD was 1000 ng/mL using the 20 or 25 ng/mL cutoff by Abbott(20), DRI(20), LZI(25), and ROCH(20). The minimum detectable concentration for 7-OH-CBD was 1000 ng/mL using the 20 or 25 ng/mL cutoff by Abbott(20), DRI(20), and LZI(25). 6-OH-CBD and 7-OH-CBD were not detected by any of the six immunoassays at the 50 ng/mL cutoff. CBD, 7-COOH-CBD, Abn-CBD, and CBDA-A were not detected by any of the six immunoassays at either the 50 ng/mL or 20 or 25 ng/mL cutoffs. The four ∆10-THC analogs were detected at 100 ng/mL using the 50 ng/mL cutoff by Abbott, CEDIA, DRI, LZI, and SYVA. The four ∆10-THC analogs were detected at 50 ng/mL using the 20 or 25 ng/mL cutoff by Abbott(20), CEDIA(25), DRI(20), LZI(25), and SYVA(20). None of the analogs were detected by ROCHE(20) and ROCHE(50). Olivetol was only detected at 1000 ng/mL by the ROCHE screening kit at both the 50 ng/mL and 20 or 25 ng/mL cutoffs. Olivetolic acid was not detected by any of the six immunoassays at either the 50 ng/mL or 20 or 25 ng/mL cutoffs. Conclusions: The six commercially available homogeneous urine cannabinoid screening kits were able to detect ∆8-THC, 11-OH-∆8-THC, 11-COOH-∆8-THC, 6-OH-CBD, 7-OH-CBD, all ∆10-THC chiral analogs, and olivetol with varying selectivity depending on the screening kit. The six commercially available homogeneous urine cannabinoid screening kits were not able to detect CBD, 7-COOH-CBD, Abn-CBD, CBDA-A, and olivetolic acid. Funding: Funded in part by National Institute of Justice (NIJ) Research and Development in Forensic Science for Criminal Justice Purposes Grant (15PNIJ-21-GG-04188-RESS)