Cannabinoid concentrations in confiscated cannabis samples and in whole blood and urine after smoking CBD-rich cannabis as a “tobacco substitute”

Abstract

In Switzerland, only cannabis with a total Δ 9 -tetrahydrocannabinol (THC) content higher than 1% is controlled by the narcotics legislation. Cannabis products rich in cannabidiol (CBD) and low in THC can be legally sold as tobacco substitutes. In this paper, we address analytical and forensic toxicological issues related to the increasing availability and consumption of these products. Based on the analysis of 531 confiscated cannabis samples, we could establish classification thresholds: plant material with a ratio of total THC/total CBD ≥ 3 is graded as THC-rich/CBD-poor, whereas samples with a ratio ≤ 0.33 are categorized as CBD-rich/ THC-poor cannabis. We also evaluated an on-site test kit as a rapid alternative to the laborious liquid or gas chromatography (LC or GC)-based techniques normally used for the differentiation between THC-and CBD-cannabis. Furthermore, we determined whole blood and urine cannabinoid levels after smoking different doses of legal CBD-cannabis. A male volunteer smoked one cigarette within 15 min and four cigarettes within 1 h and within 30 min, respectively. Cigarettes contained on average 42.7 mg CBD and 2.2 mg THC. Blood samples were collected up to 1.1 h and urine samples up to 27.3 h after the beginning of smoking. All urine samples tested negative by three immunochemical assays for detection of cannabis use. This is an important finding for abstinence monitoring. However, we found that the trace amounts of THC present in CBD-cannabis can produce THC blood levels above the Swiss legal limit for driving, and thus render the consumer unable to drive from a legal point of view.

Validation of the 4‐aminophenol color test for the differentiation of marijuana‐type and hemp‐type cannabis

“…Most importantly, these experiments also provide information on the test's limitations, allowing the characterization of the region where the test is expected to produce inconclusive results. As such, the 4‐AP color test “unreliability” region is identified as the region where the THC/CBD ratios are within the 0.3–3.0 range, confirming previous results reported by Hädener et al [11].…”

“…From the certificate of analysis provided with the samples, the ratios of THC/CBD for these samples were calculated as 0.605, 0.596, 0.517, 0.418, 0.492, 0.377, and 0.294. These ratios are all within or near the THC/CBD =0.3–3.0 window, where inconclusive color results are expected, as previously reported by Hädener et al [11].…”

“…The concentration of THC and CBD in this sample had been reported as 0.11% and 0.64%, respectively. The higher CBD concentration would be expected to produce a pink result; however, the relatively low cannabinoid concentrations may have resulted in slow reactions and inconclusive results, as previously reported by Hädener et al [11]. The overwhelming agreement between all other results obtained by DEA and DFS demonstrates the robustness of the typification test, while also confirming that the 4‐AP chemical test is not based on the actual concentration of THC, but rather the ratio of THC to CBD.…”

“…The applicability of the FBB and FBBB salts as visualization reagents during TLC analyses has also been demonstrated in the literature [9,10]. [11] showed that this colorimetric test was successfully applied to distinguish between CBD-rich and THC-rich cannabis samples. To conduct the differentiation, a small sample of dried or fresh cannabis plant material is transferred into a vial, reagents are added, and then, the reaction is observed within 2 min.…”

Interpol review of controlled substances 2016–2019

“…2019 13-loci STR multiplex system for individualization and origin differentiation of Brazilian seized samples of marijuana [ 716 ]; determination of Cannabinoid concentrations in 531 confiscated cannabis samples [ 717 ]; optimization of protein extraction from cannabis [ 718 ];…”