An Enhanced LC–MS-MS Technique for Distinguishing Δ8- and Δ9-Tetrahydrocannabinol Isomers in Blood and Urine Specimens

Abstract

Among the abundance of cannabinoids identified in cannabis, the active parent drug, Δ9-tetrahydrocannabinol (Δ9-THC), and its oxidized metabolite, 11-nor-9-carboxy-Δ9-THC (Δ9-THCCOOH), are attractive analytical targets to detect cannabis use. More recently, confirmation of these analytes may be hindered by a related interfering compound. Forensic toxicology laboratories attribute this phenomenon to an increase in cases containing Δ8-tetrahydrocannabinol (Δ8-THC) and 11-nor-9-carboxy-Δ8-THC (Δ8-THCCOOH). It is technically challenging to chromatographically resolve and accurately quantify Δ8- and Δ9-THC and THCCOOH in toxicology specimens due to their structural resemblance. This study describes a validated method to resolve and quantify active Δ8-THC and Δ9-THC in blood while qualitatively confirming the inactive metabolites Δ8-THCCOOH and Δ9-THCCOOH in blood and urine. Analytes are extracted and concentrated by solid-phase extraction and analyzed by liquid chromatography electrospray ionization tandem mass spectrometry, which is amenable to modern toxicology laboratory routine workflows. This procedure offers a clear solution to untangling mixtures of these isomers, particularly in cases where Δ8-THC and its metabolite are the sole or dominant form.

Analysis of Cannabinoids in Biological Specimens: An Update

“…This isomer has been identified by GC-MS, but it is common to obtain interfering peaks for ∆ 8 -THC and 11-nor-9-carboxy-∆ 8 -tetrahydrocannabinol (∆ 8 -THC-COOH) isomers [8]. Considering their structural resemblance (as seen in Figure 1), it is extremely difficult to accurately quantify ∆ 8 and ∆ 9 isomers in toxicological analysis [41].…”

“…The team of Chan-Hosokawa [8] noticed several cases of overlapping peaks in cannabinoid confirmation tests using LC-MS/MS. These cases cannot be considered since they do not meet the acceptance criteria and can lead to false positive or inconclusive results [41]. Thus, the group developed an analytical methodology to separate ∆ 8 and ∆ 9 isomers and their metabolites in blood samples.…”

“…Likewise, Reber et al [41] developed an analytical methodology to quantify ∆ 8 -THC, ∆ 9 -THC, ∆ 8 -THC-COOH, and ∆ 9 -THC-COOH in blood and urine samples with a SPE-LC-MS/MS methodology. While ∆ 8 -THC and ∆ 9 -THC results were satisfactory, a deuterated form of ∆ 8 -THC-COOH would help increase accuracy values for the study of the carboxylated isomers.…”

Delta‐8 tetrahydrocannabinol: a scoping review and commentary

“…Chemically determining if THC is delta-8 or delta-9 is difficult, costly and time-consuming [2,5,17,27,45,47,[95][96][97][98][99][100][101][102][103]. Although in the preliminary stages of research, chromatography methods have been developed to distinguish between different manufacturing methods [89].…”

Liquid chromatography–tandem mass spectrometry for clinical diagnostics

“…With the decriminalization of marijuana and increasing use of cannabinoids in medicine and recreational products, laboratories are required to be able to distinguish between the different patterns of cannabinoid use 63 . Mass spectrometry methods have been shown to be able to differentiate Δ8-tetrahydrocannabinol (THC) and Δ9-THC in blood and urine 64 . Δ9-THC is the main psychoactive ingredient in cannabis and is illegal in the United States.…”