∆8-THC-COOH cross-reactivity with cannabinoid immunoassay kits and interference in chromatographic testing methods.

Because of structural similarities, the presence of 11-Nor-9-carboxy-∆8-tetrahydrocannabinol (∆8-THC-COOH) in a urine specimen might interfere with testing for 11-Nor-9-carboxy-∆9-tetrahydrocannabinol (∆9-THC-COOH). A set of samples containing ∆8-THC-COOH with concentrations ranging from 10 to 120 ng/mL were tested at cut-offs of 20, 50 and 100 ng/mL using cannabinoid immunoassay reagents from three different manufacturers. Cross-reactivities ranged from 87% to 112% for ∆8-THC-COOH at the cut-off of 50 ng/mL for the three different platforms. Additionally, samples containing both ∆8-THC-COOH and ∆9-THC-COOH were fortified by the National Laboratory Certification Program (NLCP). U.S. Department of Health and Human Services (HHS)-Certified Laboratories tested the samples to determine the interference of ∆8-THC-COOH on confirmatory tests commonly used in workplace drug testing laboratories for the confirmation and quantification of ∆9-THC-COOH. When evaluating confirmation and quantification of ∆9-THC-COOH in the presence of ∆8-THC-COOH, unreportable results for ∆9-THC-COOH were observed because of chromatographic interference or mass ratio failures. However, there were no false-positive ∆9-THC-COOH reports from any HHS-certified laboratory.

Conversion of water-soluble CBD to ∆9-THC in synthetic gastric fluid-An unlikely cause of positive drug tests.

Cannabidiol (CBD) has been shown to convert to ∆9-tetrahydrocannabinol (∆9-THC) in acidic environments, raising a concern of conversion when exposed to gastric fluid after consumption. Using synthetic gastric fluid (SGF), it has been demonstrated that the conversion requires surfactants, such as sodium dodecyl sulfate (SDS), due to limited solubility of CBD. Recently, water-compatible nanoemulsions of CBD have been prepared as a means of fortifying beverages and water-based foods with CBD. Since these emulsions contain surfactants as part of their formulation, it is possible that these preparations might enhance the production of ∆9-THC even in the absence of added surfactants. Three THC-free CBD products, an oil, an anhydrous powder and a water-soluble formulation, were incubated for 3 h in SGF without SDS. The water-soluble CBD product produced a dispersion, while the powder and the oil did not mix with the SGF. No THC was detected with the CBD oil (<0.0006% conversion), and up to 0.063% and 0.0045% conversion to ∆9-THC was observed with the water-soluble CBD and the CBD powder, respectively. No formation of ∆8-THC was observed. In comparison, when the nano-formulated CBD was incubated in SGF with 1% SDS, 33-36% conversion to ∆9-THC was observed. Even though the rate of conversion with the water-soluble CBD was at least 100-fold higher compared to the CBD oil, it was still smaller than ∆9-THC levels reported in CBD products labeled "THC-free" or "<0.3% THC" based on the Agricultural Improvement Act of 2018 (the Farm Bill). Assuming a daily CBD dose of around 30 mg/day, it is unlikely that conversion of CBD to ∆9-THC could produce a positive urinary drug test for 11-Nor-9-carboxy-∆9-THC (15 ng/mL cut-off).